"At the close of the second essay, there is a sketch of the outline of the theory up to the point which it has reached as yet. Of course there is still much which requires to be explained and developed. The science is only in its infancy; but still its principles can be understood and appreciated. It is taken for granted that there are no spirits but human ones, these being the only spirits of which we can have any scientific knowledge. This being assumed, Mr. Wallace proceeds to give a short analysis of human nature, drawn from generalizations from the 'phenomena in their entirety,' and the communications of the spirits themselves. This is contained in four propositions:--
"1. Man is a duality, consisting of an organized spiritual form evolved coincidently with and permeating the physical body, and having corresponding organs and development.
"2. Death is the separation of this duality, and effects no change in the spirit, morally or intellectually.
"3. Progressive evolution of the intellectual and moral nature is the destiny of individuals; the knowledge, attainments, and experience of earth-life forming the basis of spirit-life.
"4. Spirits can communicate through properly-endowed mediums. They are attracted to those they love or sympathise with.... But, as follows from Clause 2, their communications will be fallible, and must be judged and tested just as we do those of our fellow-men.