Metaphysics and Philosophy

The secretory activity of the pineal gland is only relatively understood. Historically, its location deep in the brain suggested to philosophers that it possessed particular importance. This combination led to its being a "mystery" gland with myth, superstition and occult theories surrounding its perceived function.

René Descartes, who dedicated much time to the study of the pineal gland,^[25] called it the "seat of the soul".^[26] He believed that it was the point of connection between the intellect and the body.^[27] The relevant quotation as to Descartes' reason for believing this is,

“My view is that this gland is the principal seat of the soul, and the place in which all our thoughts are formed. The reason I believe this is that I cannot find any part of the brain, except this, which is not double. Since we see only one thing with two eyes, and hear only one voice with two ears, and in short have never more than one thought at a time, it must necessarily be the case that the impressions which enter by the two eyes or by the two ears, and so on, unite with each other in some part of the body before being considered by the soul. Now it is impossible to find any such place in the whole head except this gland; moreover it is situated in the most suitable possible place for this purpose, in the middle of all the concavities; and it is supported and surrounded by the little branches of the carotid arteries which bring the spirits into the brain.”^[25] (29 January 1640, AT III:19-20, CSMK 143)

"For he [Descartes] maintained, that the soul or mind is specially united to a particular part of the brain, namely, to that part called the pineal gland, by the aid of which the mind is enabled to feel all the movements which are set going in the body, and also external objects, and which the mind by a simple act of volition can put in motion in various ways...Such is the doctrine of this illustrious philosopher (in so far as I gather it from his own words) ; it is one which, had it been less ingenious, I could hardly believe to have proceeded from so great a man. Indeed, I am lost in wonder, that a philosopher, who had stoutly asserted, that he would draw no conclusions which do not follow from self-evident premisses, and would affirm nothing which he did not clearly and distinctly perceive, and who had so often taken to task the scholastics for wishing to explain obscurities through occult qualities, could maintain a hypothesis, beside which occult qualities are commonplace. What does he understand, I ask, by the union of the mind and the body?" (Baruch de Spinoza, Ethics; part 5)^[28]

The notion of a 'pineal-eye' is central to the philosophy of the French writer Georges Bataille, which is analyzed at length by literary scholar Denis Hollier in his study Against Architecture.^[29] In this work Hollier discusses how Bataille uses the concept of a 'pineal-eye' as a reference to a blind-spot in Western rationality, and an organ of excess and delirium.^[30] This conceptual device is explicit in his surrealist texts, The Jesuve and The Pineal Eye.^[31]

In Discordianism it is maintained that the pineal gland allows one to consult with the goddess Eris.^[32]