2. If we wish to deserve success in the study, it will in the first place be necessary to spare no pains, but to exert the mind to the utmost, in clearing and winning those things which closely surround and are subordinate to the subject in hand. The anatomical scrutiny of animal bodies, and especially of the cerebrum, cerebellum, medulla oblongata, and spinal marrow, and also of the nerves, must open the doors which lead to it. Without a thorough command of these portals, it is in vain to hope to penetrate the recesses of nature's temple. It is impossible to divine what nature is in the invisible sphere, excepting from what she is in the visible; or what she is in causes, excepting from what she is in those effects which ultimately strike some one of the senses. Just so it is impossible to know the nature of the inner action of the mind, without examining the face of the mind, that is to say, without investigating the brains and marrows of the mind. And even then it will still be impossible to guess how the soul unfolds her forces, without having studied the connections of all the viscera of the body, as well as the organs of the external senses, which contribute in their degree to enable those of the internal senses to undergo that development which will open them to the soul.
