Fig. 3. Illustrates the act of seeing. The object ABCD forms an image, 1357, on the retina of the eye. This image provokes a similar image, 2468, on the wall of the brain’s ventricle, by exciting a stream of ›spiritus animalis› from the central ventricle through certain of the fine nerve tubules of the optic nerve, the openings of the nerve tubules in the wall of the ventricle being widened and thus forming images (of sight), which the soul is able to perceive from its seat in the pineal gland. Fig. 4. Reproduced from Vieussens: ›Neurographia universalis›, Tabula XVI. Illustrates the passage of the coarse fibres of the _middle region of the brain’s medullary substance_ through the capsula interna, pons and the pyramids on the front of the medulla oblongata downwards to _the anterior part of the spinal cord_.] To the anterior region he attributed the actual operation of the soul, while he supposed that the posterior region was chiefly engaged in the animation of the blood. He adds, however, ›it cannot be denied that sensations reach even the posterior region of the brain, yet our mind does not become conscious of them to the same degree as it does in the anterior region› (›The Brain›, No. 71). In this _anterior region of the cerebrum_ he distinguished _three lobes_, or so called ›curiae›, the first one highest up, ›in the crown›, a middle one below it, and a third one lowest down, _i. e._, nearest to the fissure of Sylvius.[73] In these three lobes the actual psychic life is developed, and that so much the more clearly and perfectly, the higher up in the region these intricate processes occur. It is here that perceptions, thoughts, judgments, conclusions, come into being; it is from here that ultimately will and determination issue. (See ›The Brain›, Nos. 12, 66, 71, 88, 98, 100, 102). As regards the sensory part of the psychic activity, SWEDENBORG does not make any attempt at a detailed localization; but as regards the motor functions he arranges their centres within the above-mentioned regions as follows: ›_The muscles and actions_ which are _in the ultimates of the body_ or in the soles of the feet seem to depend more immediately _upon the highest parts_ (_of the brain_), upon _the middle lobe_ the muscles which belong to _the abdomen and thorax_, and upon the _third lobe_ those which belong to _the face and head_;› and he adds, ›for they seem to correspond to one another in an inverse ratio› (›The Brain›, No. 68).