Readers know well the recent outpouring of books about brain function, consciousness, cognition, and the relationship between brain and behavior. Along with these have come some mainly academic books on the history of neuroscience and the brain. What has been lacking until now has been a solid but accessible historical overview. Stanley Finger’s new work, Minds Behind the Brain: A History of the Pioneers and Their Discoveries, ﬁlls this void. A professor of psychology at Washington University in St. Louis, Finger is also author of the extremely useful and encyclopedic Origins of Neuroscience: A History of Explanations into Brain Function (Oxford University Press, 1994). As a leader of the International Society for History of Neuroscience and co-editor of its Journal of the History of Neurosciences, Finger has devoted much of his career to studying the history of the brain. In this new book, Finger uses biographies—beginning with ancient Egyptian observers and ending with contemporary neuroscientists—to draw readers into the lives of researchers even as he teaches often complex concepts of neuroscience and neuroanatomy. The result is an extremely readable, richly illustrated, and comprehensive history. By the time readers complete the book, they will not only gain a comprehensive overview of the history of brain research, but also learn a good deal about the mechanisms of the brain. This approach could provide a model for a multi-part television documentary series that would educate and fascinate viewers.
Minds Behind the Brain is divided into 18 chapters, 16 of which focus on an individual or group of individuals whose views are inﬂuential on those who follow. The story is presented as one of linear progress. While many readers will ﬁnd this approach refreshing, professional historians of science may be dismayed because Finger’s interpretation of history does not take into account recent debates about the extent to which scientiﬁc theories are inﬂuenced by cultural values and assumptions, rather than simply by a disinterested process of discovery.
FROM THE HEART TO THE HEAD
Early chapters focus on the literal discovery of the brain and its putative role as the seat of human consciousness. We learn that even though ancient Egyptians began to develop a rudimentary knowledge of nerves and performed simple surgery on the brain, they nevertheless “looked upon the heart, not the brain, as the central organ of the body and the seat of the soul.” The Greeks connected the soul with the brain, but, as Finger demonstrates, each era of ancient Greek history provided a different interpretation of human consciousness. Like the Egyptians, the Greeks described in Homer’s Iliad believed that the heart was the central organ of their soul. Finger ﬁnds very little self-awareness in early Greek mythic ﬁgures. The movement from heart to head did not emerge until the Classical age in Greece, especially in the writings of Hippocrates (c. 460-377 BC). Using what little may be known of Hippocrates’ life, Finger describes the transition toward the Hippocratic view “that the brain is the major controlling center for the body.” As Hippocrates was alleged to have written: “Men ought to know that from nothing else but the brain come joys, delights, laughter and sports, and sorrow, griefs, despondency, and lamentations. And by this, in an especial manner, we acquire wisdom and knowledge, and we see and hear and know what are foul and what are fair.”
Not until the Alexandrian era, however, did the Greek physician and anatomist Galen (c.130-216 AD) provide the ﬁrst anatomical studies of the brain, which were based on examination of wounded gladiators and on animal, but not human, dissection. Galen was the ﬁrst to associate disease with speciﬁc organs. But, as Finger tells us:
Galen’s inability to dissect human brains, combined with a willingness to generalize from the brains of barnyard animals to humans, led him to draw some incorrect conclusions about human neuroanatomy and neurophysiology.
Nevertheless, Finger credits these experiments as “instrumental in leading many learned men away from the older but still competing idea...that intellect, reason, and perception are functions of the heart.”
AN ANATOMICAL REVOLUTION?
Galen’s theories remained inﬂuential for the next 1300 years, but those neuroanatomists who drew on them also began to expose contradictions in Galen’s reasoning. By the time that Andreas Vesalius (1514-1564) began his neuroantomical studies in Italy, these contradictions had become apparent; but respect for the authority of Galen’s work resulted in scholastic “gymnastics” instead of real theoretical challenges. For instance, Vesalius’s mentor, the Parisian anatomist Jacobus Sylvius, defended Galen’s anatomy, arguing that “even if some of his [Galen’s] facts may not hold in the present, [his anatomy] had been perfect for the second century.”
Vesalius’s work, especially the Fabrica (1543), was the ﬁrst dramatic break with Galenic anatomy because it was based on actual human brain dissection. In particular, Vesalius rejected the view that different functions of the mind could be tied to so-called spirits in the ventricles of the brain. But the dominant inﬂuence of Galen remained so powerful that Vesalius was attacked as a madman by some of Europe’s most inﬂuential scholars, including his own teacher, Sylvius, in 1551.
Here Finger endorses the view that Vesalius led a Renaissance revolution emphasizing unbiased observation over theory and that Vesalius’s long-term contribution was to establish the centrality of modern anatomy in understanding the brain. Other recent historical investigators have, however, suggested a different reading of Vesalius’s intentions. For instance, Andrew Cunningham argues that Vesalius, like his critics, was less interested in establishing unbiased human observation than in searching for a way to illustrate the reasonableness of God’s creation. To achieve this, Vesalius drew on Galen’s practice of dissection but rejected many of Galen’s conclusions, because Vesalius was certain that animal brains could not serve as a model for humans. In so doing, he inadvertently resurrected an older tradition: “Vesalius the Modern,” writes Cunningham, “had become an Ancient; he has recreated an ancient practice—the practice of human anatomy.”1
Although the difference between Finger’s interpretation and Cunningham’s may seem trivial, they reveal contrasting reasons for the acceptance and persistence of René Descartes’ philosophical sundering of mind and body. For Finger, the answer is found in Descartes’ life history. Descartes, according to Finger, was an unconventional individual whose experiences in the Thirty Years War shaped his view of human nature and inﬂuenced his theory of dualism. From this perspective, Descartes was connected to earlier Renaissance ﬁgures, such as Vesalius, based on his theories on human observation. What separated the two men was the nature of their observations, not their commitment to empiricism.
In contrast, Cunningham views Vesalius and Descartes as sharing an ideology. Both men, according to Cunningham, drew on what was known about the brain as evidence for human uniqueness and for divine creation. Thus, Descartes and Vesalius shared a similar world view and were both attempting to distinguish animals from humans, albeit through very different methods. While Vesalius made the separation based on the results of his animal and human dissections, Descartes emphasized language as a unique human feature. Descartes’ famous assertion in Discourse on Method (1637), “Je pense, donc je suis,” distinguished animals and humans—because unlike humans, brute animals could not think and had no language. This view of the brain, therefore, could be used to reinforce evidence of the existence of God.
Ironically, one fascinating discovery elaborated by Finger could be used to support Cunningham’s point of view. Writers have long maintained that Descartes argued for human uniqueness based on anatomical evidence—saying that, unlike other brain structures, there was no redundancy of the pineal gland and that this putatively human brain structure must be the seat of the soul. However, Finger convincingly demonstrates the falsity of this persistent claim. Descartes did not believe that the human soul was housed in the pineal gland because of its uniqueness to humans. Rather, like the Renaissance anatomists, Descartes was committed ﬁrst to the belief in human uniqueness. He chose the pineal gland as the site of the soul because, like the anatomists, he assumed that similar organs had different functions in animals and in humans.
As Finger’s narrative shows, scholarly theories advanced side-by-side with anatomical discoveries. Most often, as with the case of the seventeenth-century English physician Thomas Willis, anatomists paid homage to Galen’s theories and the Cartesian separation of mind and body while at the same time they pursued anatomical studies that Finger believes ultimately undermined these theoretical assumptions. An interesting question is whether these changes were the result of individual idiosyncracies, which would mesh with with Finger’s biographical approach, or came from anomalies in major theoretical constructs, as suggested in the writings of the late Thomas Kuhn.
Finger’s evaluation of Willis often seems inﬂuenced by current mindsets. Willis’s accomplishments are tested against present day standards and knowledge, rather than being put in a wider historical context. Finger praises Willis for “correctly [differentiating] between cerebral functions, such as memory and volition, and lower-brainstem functions, such as control over respiration and heartbeat” and for having “correctly associated the corpus striatum with motor functions and ﬁrst discussed different levels of neural control.” Willis also described a number of neurological and psychiatric disorders including bipolar disorder, narcolepsy, and myasthenia gravis.
Finger gives Willis “great credit for refocusing attention on the brain itself.” While he reminds us that Willis was “a starry-eyed optimist who made his share of errors:”
Willis shows that he also could be misled. He looked for an everyday action that would reveal the link between memory and the uppermost part of the brain. He was sure that he had found one when he observed people rubbing their temples or foreheads while endeavoring to remember a fact. Today we realize that such actions reveal nothing at all about the underlying brain.
Finger concludes that, on balance, “his shortcomings appear small when we look at the scope of his work and the bigger picture.” Willis’s greatest legacy, writes Finger “was his ability to stimulate others to test and improve his ideas.” Finger adds that none of Willis’s achievements would have been possible “had he separated the mind and body in the manner of Descartes.” Since, as Finger tells us, Willis agreed with Descartes that only humans possessed souls, it makes one wonder about the supposed transcendent inﬂuence of Descartes.
FROM NERVES TO LOCALIZATION
The strength of Finger’s biographical approach is that it allows him to focus on what may be the most important scientiﬁc contributions to our current understanding of the brain. Its limitation is that the history is not seamless; scientiﬁc progress does not occur in a neat, linear fashion. Still, this is a small compromise because the purpose of Minds Behind the Brain is less to create a comprehensive history than to educate readers in basic neuroscience through the stories of some of its key players. From this perspective, the chapter on Luigi Galvani (b. 1737) is a tour de force.
Finger traces the history of electrical experiments from prior to Galvani, but focuses on Galvani’s study of electrical conduction by the nerves. Here we learn how earlier notions of nerve actions changed from ethereal spirits, ﬂuids, and vibrations to a fascination with electricity. By the end of the eighteenth century, studies of electric ray ﬁsh and the development of the Leyden Jar (1745) made controlled experiments more feasible. Activating frog nerves with electricity, Galvani was able to induce a seemingly natural muscle contraction, reinforcing his view that there was something called “electrical ﬂuid” responsible for nerve conduction. Galvani also experimented with atmospheric electricity, attaching lightening rods to frogs’ legs (similar to Benjamin Franklin’s famous kite experiment).
From these experiments, Galvani concluded that “two dissimilar metals making contact with a nerve attached to a muscle can make the muscle contract.” Finger suggests that “Galvani probably began his work with few preconceived notions, but he clearly developed a thesis as he progressed.” Thus, Galvani’s experiments reinforced his belief that animal electricity was released from the brain and distributed through nerves to the muscles.
Although his work ultimately would inﬂuence research and treatment well into the 1800s, Galvani achieved little fame in his lifetime. By the early 1790s, Alessandro Volta, an inﬂuential professor at the University of Pavia, had rejected Galvani’s experiments and his claims about the existence of animal electricity. As a result, the initial inﬂuence of Galvani’s discoveries was primarily on ﬁction writers, such as Mary Shelley, and pseudo scientists, such as Anton Mesmer. But, by the mid-nineteenth century, electrical currents were used for a variety of treatments, especially for those suffering from a variety of mild nervous disorders.
A contemporary of Galvani, Emanuel Swedenborg (1688-1772), the Swedish mathematician turned physician (and later religious leader), was probably the ﬁrst to develop a comprehensive theory that localized functions in various areas of the brain. But Swedenborg’s work remained obscure and would only be rediscovered in 1868, by which time the concept of localizing functions was no longer a novelty.
Thus the credit for originating brain localization is generally bestowed on Franz Joseph Gall (1758-1828), whose story Finger traces. He reminds us that Gall’s theories about the faculties of the mind were based not merely on descriptions of protrusions of the skull, but also on assumptions about the structures that underlay them. Like so many of his predecessors, Gall insisted there were a number of faculties— such as wisdom, sense of metaphysics, satire and wit, poetic talent, kindness and benevolence, mimicry, religious sentiment, and ﬁrmness of purpose—that were distinctly human. But Gall’s main contribution may have been his success in breaking the Cartesian duality of mind and body by arguing that these faculties, as well as those shared with animals, could be located in a speciﬁc part of the actual physical body. Although Gall’s “organology,” transformed by his follower Johann Spurzheim into “phrenology” (a term that Gall rejected), is no longer taken seriously, its basic assumption of localization of function is still at the center of an increasingly sophisticated debate.
Whatever quibbles one may have with Finger’s ambitious undertaking in Minds Behind the Brain, there are new gems of neuroscience history in almost every chapter.
Whatever quibbles one may have with Finger’s ambitious undertaking in Minds Behind the Brain, there are new gems of neuroscience history in almost every chapter, such as his revision of the allegations about Descartes’ view of the pineal gland. Finger presents a compelling account of the common claim that in 1836 Montpellier physician Marc Dax had recognized the importance of the left hemisphere for speech. Finger concludes that Dax never published or even presented his ﬁndings to any professional audience.
Dax might have recognized the importance of the left hemisphere for speech well before he [Broca] did, but then Dax must have lost the courage to present his surprising findings to the public.
Finger also sees Gustav Fritsch and Eduard Hitzig’s landmark 1870 discovery of the cortical motor area as providing the springboard for subsequent researchers, including James Crichton-Browne, David Ferrier, and John Hughlings-Jackson, all of whom would search for the cortical bases of psychological behaviors. These later researchers speculated about the difference in function between the “higher” and “lower” cortical areas. Based on Hughlings-Jackson’s discussion of the role of higher cortical areas in supressing limbic functions, Freud would develop his early theories of repression.
FROM SYMPTOMS AND SIGNS TO SPLIT BRAINS
Although the book’s chapters build on one another, many could stand alone as comprehensive essays on a particular neuroscientist or era. One of the very best chapters is on Jean-Martin Charcot, probably the most inﬂuential neurologist of the late nineteenth century. If one were to recommend one brief, but comprehensive, English-language overview of Charcot’s many contributions—the identiﬁcation of multiple sclerosis, Parkinson’s, amyotrophic lateral sclerosis, Tourette’s syndrome, and hysteria —Finger’s chapter would sufﬁce.
Finger has a ﬁne grasp of the context in which Charcot attacked a neurological mystery. He describes how Charcot would begin with careful description of a patient’s clinical signs, looking always for a neurological basis. If no such basis for a behavior could be located, as with patients with tics, Charcot would carefully identify the signs most common to a subset of similar patients. From these descriptions, he would construct a syndrome, with the hope that the signs associated with that syndrome might one day reveal a common cause and, in the short run, would at least provide a basis for common treatment of patients with similar behavioral features. Finger also demonstrates his deep familiarity with the brain and the nervous system as he reminds us of the extent to which Charcot’s work laid the groundwork for understanding the neurological basis of some extremely confusing sets of symptoms and signs.
One of the most difﬁcult concepts for laymen to comprehend is cellular biology. Understanding the types and interactions of neurons in the brain is even more daunting. Of all the chapters in this excellent book, I ﬁnd Finger’s discussion of the discovery of neurons the most useful antidote to such difﬁculties. Focusing on the 1906 Nobel Prize winning experiments of Santiago Ramón y Cajal, Finger lays out the history of microscopy and cell staining. Readers unfamiliar with either will learn how the new technologies yielded revolutionary understandings of cell functions, which in turn made it possible to develop more complex experiments on normal and abnormal brain functioning.
The biographies in Minds Behind the Brain also supply the reader with a personal context that humanizes the researcher, making the research discussed more accessible. Certainly that is the case with Finger’s discussion of the life of Charles Scott Sherrington (1857-1952). We learn how Sherrington’s shyness combined with his early education and the inﬂuence of his physician stepfather to move him toward laboratory medicine—pathology and immunology— and ultimately into a curiosity about the nervous system.
Unlike other brain pioneers, Sherrington started with research on the spinal cord and worked his way up to the brain. As a result, he was able to elucidate the knee jerk reﬂex and the supply of nerves in the muscles around the joints, and to develop an integrative theory of neurophysiology. All of these discoveries become important for the diagnosis and treatment of a variety of behavioral and physiological changes found in brain-damaged patients.
The ﬁnal chapters of the Minds Behind the Brain examine more recent contributions including the development of the EEG (Edgar Douglas Adrian, 1897-1977, and his colleagues); the discovery of neurotransmitters (Otto Loewi, 1873-1961, and Henry Dale, 1875-1961); and neuronal growth and split brain experiments (Roger W. Sperry, 1913-1994, and Rita Levi-Montalcini, b. 1909). In particular, the discussion of Sperry’s split brain experiments is the best on this topic for a general audience. In the late 1960s, Sperry and his graduate student Michael Gazzaniga tested a series of patients who, to relieve their intractable epilepsy, had an operation severing their corpus callosum, thus separating the connections between the brain’s hemispheres. As a result, the patients could see objects in their right visual ﬁeld but now lacked the neurological connections to the left hemisphere that enabled them to have access to language. What Sperry and Gazzaniga found was that the right (non-dominant) hemisphere, though speechless, had a mind of its own.
Sperry’s elegant split brain studies, relying on patients with neurological malfunctions, opened the way for a series of other investigations that would tell us a great deal about the functioning of normal brains. Although there were many other important roots of the explosion in neuroscientiﬁc research that would follow, Sperry’s contribution was immense because it provided a neurological basis for exploring the age-old issue of consciousness.
WHEN GIANTS EMERGE
In his ﬁnal chapter, Finger asks what lessons can be drawn from the combined biographies of these brain pioneers. Although he ﬁnds common features, including an “intense drive to learn and keep abreast of new developments,” Finger admits that “their basic personalities were anything but cast from a single mold.” Reframing his question, Finger then wonders if what best ties his group together may be that each successive generation was able to “stand on the shoulders of giants.” But Finger concedes that “in reality, the idea that succeeding generations of scientists can see further standing on the shoulders of giants is a partial truth. Typically, giants emerge only when others are already beginning to question existing theories and ideas.”
Failing that explanation to tie the stories together, Finger suggests, “Clearly, our pioneers lived when the Zeitgeist, or spirit of the times, was such that their ideas did not fall upon deaf ears.” To this Finger adds, drawing on Stephen Jay Gould, that some times are more ripe for change than others, especially when “there is less rather than more resistance to new ideas, mainly because of cultural changes, technological advances, and ground-tilling by other scientists.” And, Finger concludes, in all these cases there is the need for a mind prepared to receive those ideas. He endorses the statement of the nineteenth-century American scientist Joseph Henry that “The seeds of great discovery are constantly ﬂoating around us, but they only take root in minds well prepared to receive them.”
Taking nothing away from Finger’s achievement in Minds Behind the Brain, readers will be hard-pressed to ﬁnd in this book much information about the social and cultural changes, technological advances, and evidence of a prepared mind that Finger believes enable the discoveries that he describes. Cultural factors may be part of the story, but attempting to elucidate them in this book most likely would have taken away from Finger’s unique contribution. For what Finger does best is to provide a vehicle for general readers to comprehend the complex mechanisms and physiology of the brain from the cell to the organism through stories about the brain’s major discoverers.
There are, as Finger knows well, competing historical interpretations of the meanings of the lives and the discoveries he illuminates. Others have and will continue to explore these controversies. But no one else has been able to match Finger’s extraordinary ability to explain in an accessible format what we have learned about the brain. For this alone, we should be grateful.
From Minds Behind the Brain: A History of the Pioneers and Their Discoveries by Stanley Finger. © 2000 by Stanley Finger. Reprinted with permission of Oxford University Press.
A FREQUENT MISINTERPRETATION
Before we turn to how Descartes’ solution to the mind-body problem was received, one point about the choice of the pineal gland as the seat of the soul should be clarified. Some authors have stated that Descartes also selected the pineal gland because he believed this tiny gland was unique to humans, the only organism with a soul. This assertion, however, is a misinterpretation of the philosopher’s thoughts.
Descartes must have known that animals have pineal glands. The gland was described as a basic part of animal anatomy in books written by respected authorities familiar to the philosopher. One such person was Galen. In the year 177 as we have seen, Galen described how to find the pineal gland when systematically dissecting the brain of an ox (Chapter 4). Similarly, the pineal gland was described in sheep by Renaissance anatomist Andreas Vesalius (see Chapter 5).
There exists, however, even more convincing evidence to show that Descartes must have seen the pineal in freshly killed animals with his own two eyes. Specifically, he complained that this gland is much easier to find in animals than in humans, a statement that still holds true today. This is because the pineal tends to calcify (early anatomists preferred “turns to sand”) relatively early in life in humans. In a letter penned to Father Mersenne on April 1, 1640, Descartes explained:
Three years ago at Leyden, when I wanted to see it (the pineal) in a woman who was being autopsied, I found it impossible to recognize it, even though I looked very thoroughly, and knew well where it should be, being accustomed to find it without difficulty in freshly killed animals.
Earlier the same year Descartes sent a letter to the physician Lazare Meyssonier. He presented his thoughts on memory and the pineal gland, and postulated that the pineal may be less mobile in people whose minds are “sluggish.” He then went on to discuss very bright minds and here made another direct reference to the gland in animals:
As for very good and subtle minds, I think their glands must be free from outside influence and easy to move, just as we observe that the gland is smaller in man than it is in animals, unlike the other parts of the brain.
Unfortunately, Descartes was less than clear about animals having pineal glands in his major treatises. But as his letters show, he never meant to imply that humans are unique because they alone possess a pineal gland. His point was simply that only the human pineal gland can be associated with a special inhabitant—an inhabitant called the rational soul, a spiritual entity missing from all other living creatures.
REACTION TO THE THEORY
A number of open-minded physicians embraced the concept of the body as a machine. One early supporter was Louis de la Forge, and another, at least on many points, was Henricus Regius, a professor of medicine at the University of Utrecht. Regius was especially intrigued by the idea that all animal behavior and some human behavior could be reduced to simple cause-and-effect actions and treated scientifically.
The more humanistically oriented philosophers were somewhat slower than Regius to accept the idea that the body might work like a complex machine, yet the idea gradually found its share of supporters. The French took the lead, but national boundaries meant little as this new, mechanistic orientation toward the physical body took hold and spread across Europe.
Nevertheless, Descartes’ solution to the mind-body problem disturbed more than a few thinkers. The interaction of a nonmaterial substance with a physical machine was seen as hopelessly contradictory by many of his scientific and medical critics. Even some of his admirers had trouble warming up to his interactionism.
Books have been written about the criticisms of the clergy, the battles fought at universities, and even the trials that took place in municipalities between the old guard and the revolutionary Cartesians, as they came to be known. To appreciate more fully how some members of the medical and scientific communities felt about the new model, let us look in greater detail at two central issues. The first will be the reaction to Descartes’ selection of the pineal gland as the seat of the soul, and the second will be the separation of humans from the brutes.
THE LOGICAL SEAT OF THE SOUL?
To most anatomists and physiologists, the elevation of the pineal gland to its lofty position as seat of the soul made little sense. Among the first men of medicine to criticize this selection were Christophe Villiers and Lazare Meysonnier. Through Father Mersenne, they explained to Descartes that his choice of the pineal gland cannot possibly be correct. Postmortems had been performed on individuals who exhibited “stones,” “chalk,” and other deformities of this structure. Yet the minds of these men and women often seemed perfectly fine before they died.
These French physicians also thought the pineal gland was too small for the noble function assigned to it. In fact, Villiers went on to suggest that the cerebellum was the more logical candidate for the job. Others interjected that the true seat of the rational soul must be far bigger in humans than in the brutes. Indeed, pineal size differences across species, with humans on the short end, had been noted by Andreas Vasalius. In his celebrated Fabrica of 1543, he decried: “I wish that a sheep’s brain be at hand, since it shows the gland...more distinctly than does the human head.” Descartes could hardly disagree after witnessing human autopsies in Leiden, but reasoned that a smaller pineal made more sense for humans, since it would be easier for the soul to move a small object than a large one. This logic, however, was not particularly convincing to many of the intellectuals who were pondering the issue.
Thomas Bartholin, a Danish anatomist, not only brought up the issue of size but also mentioned a host of other reasons why the pineal theory should be discarded. The fanciful idea that the pineal is a mobile structure capable of dancing like a balloon above a flame was one of several issues he singled out for severe criticism. This assertion, he said, was complete nonsense, as was the notion of ventricular pores and valves for the dissemination of the spirits. These structures had never been seen; even skilled anatomists well equipped for the search could not find them. Another problem for the theory, remarked Bartholin, was the discovery of cerebrospinal fluid in the ventricles. Any watery fluid, he noted, would impair the movements demanded of the gland.
To some of his more scholarly critics, Descartes’ pineal theory also had an all-too familiar and archaic ring. The notion of pineal gland movements regulating the flow of animal spirits probably originated with Herophilus, the Alexandrian anatomist who lived around 300 B.C. (Chapter 3). Several hundred years later, Galen would write in his own disparaging way that the idea that the pineal could rise and fall to regulate the flow of spirits within the ventricles is absurd:
The notion that the pineal body is what regulates the passage of the pneuma is the opinion of those who are ignorant...since this gland...is by no means part of the encephalon and is attached not to the inside but to the outside of the ventricle, how could it, having no motion of its own, have so great an effect on the canal?...Why need I mention how ignorant and stupid these opinions are.
Nevertheless, some later scientists— Renaissance physiologist Jean Fernel among them—continued to keep the ancient idea from falling into complete oblivion. True, Descartes modified and further developed the model, but to some scholars his efforts were no more than just another variation on a theme that should have been discarded centuries earlier.
Hence, the pineal theory proposed by Descartes was seen as hopelessly naive, unreal, and even unoriginal by many intellectuals in the seventeenth century, including Nicolaus Steno. In 1665 he gave a lecture in Paris in the house of Monsieur Thévenot in which he explained that Descartes’ theory was physiologically too speculative and made no sense. Steno, a Danish anatomist, had more to say about Descartes in later years. In 1680 he wrote: “Descartes’ method is praiseworthy, but blameworthy is a philosophy where the author forgets his own method and takes that for granted which he has not yet proven by reason.”