When thou examinest the first ventricle thou wilt see three things before thou comest to the second ventricle. [_a_] The first is itself double, and is formed of the very substance of the brain, so that it forms the base of the anterior ventricle both right and left [= corpora striata]. [_b_] To the side of this is another thing like a subterranean worm, red as blood, yet tethered by certain ligaments and nervelets [= choroid plexus and taenia semicircularis]. And this worm when it lengthens itself closes these passages, and thus blocks the path between the first ventricle and the second. Nature has wrought it thus, so that when a man wills he may cease from cogitation and thought; and similarly when, on the other hand, he would think and contemplate, this worm contracts itself again and opens these passages and thus frees the way between one ventricle and another. [_c_] The third structure is a little lower and is a _lacuna_ or rounded concavity [= infundibulum]. In the middle of this is a hole which passes down towards the palate, and this lacuna provides also a direct passage which descends from the middle ventricle to its _colature_ [= sieve-like structure, i.e. certain parts of the sphenoid bone]. And this lacuna has around it certain large round eminences which support the veins and arteries that ascend to the ventricle. This passage is wide above and narrow below, and by it the first and second ventricles purge themselves of their superfluities, but the anterior part [of the first ventricle] purges itself more by the colature of the nose [= cribriform plate]. Thus nature has made two passages to cleanse the superfluities of the brain. When thou hast seen these three structures there will appear the second or middle ventricle which is as a passage and transit from the anterior to the posterior ventricle. Here are two faculties. One, the _estimative_, deduces [Italian _elicere_] the insensible from the sensible. The other, called the _cognitive_, comprehends both things sensible and things insensible, synthesizing and analysing them (_componendo e dividendo_). These [two] faculties in the middle ventricle minister to the intellect. Now all the other faculties described, and even the power of memory, are found in brute animals, but this [intellectual power] is encountered in man alone.