I have already referred to phrenological works for a list of the faculties of the human mind, so far as they have been proved to be elementary by observation of the brain. The enumeration is not complete, nor are the functions of all of them delineated with scientific precision. Improvement is expected in both particulars; but the essential character and sphere of activity of each appear to me to be so far ascertained, that we may draw inferences from them, which, although liable to be modified in consequence of subsequent observation and analysis, will probably not be altered in their essential aspects. I now proceed to inquire into the extent to which these faculties enable us to discover the ultimate elements of our own nature and that of the external world.

In treating of our own nature, let us begin by considering the mind.

1st, I repeat the observation, for it is practically too little attended to, that Mind in the sense of spirit, or of an entity existing and acting in this world independently of matter, is absolutely unknown to us. We are conscious only of mental states and acts, and these have been ascertained always to depend in this life on corresponding conditions and actions of the brain.