The originality of Descartes' theory about the pineal gland.

René Descartes thought that the pineal gland is the part of the body with which the soul is most immediately associated. Several prominent historians (such as Soury, Thorndike and Sherrington) have claimed that this idea was not very original. We re-examine the evidence and conclude that their assessment was wrong. We pay special attention to the thesis about the pineal gland which Jean Cousin defended in January, 1641.