It seems likely, however, that, since Caspar Bartholin died in 1629 and Franciscus Sylvius only started medicine in 1632, these words are by either Caspar's son Thomas Bartholin or Franciscus Sylvius himself. In 1663 in his "Disputationem Medicarum", Sylvius described the lateral fissure: "Particularly noticeable is the deep fissure or hiatus which begins at the roots of the eyes (oculorum radices) . . . it runs posteriorly above the temples as far as the roots of the brain stem (medulla radices). . . . It divides the cerebrum into an upper, larger part and a lower, smaller part".