3. In organic evolution the bodily _form_ and _structure_ must continually change in order to keep in harmony with the ever-changing environment. In other words, organic evolution is by continual change of species, genera, families, etc. There must be continual evolution of new forms by modification. In human evolution, on the contrary, and more and more as civilization advances, man modifies the environment so as to bring it into harmony with himself and his wants, and therefore there is no necessity of change of bodily form and structure or making of new species of man. Human evolution is not by modification of _form_--new species; but by modification of spirit--new planes of activity, _higher character_. And the spirit is modified and character elevated, not by _pressure_ of an _external physical environment_, but by the _attractive_ force of an _internal spiritual ideal_. 4. The way of evolution toward the highest--i. e., from protozoan to man and from lowest man to the ideal, the divine man--is a very _straight and narrow way_, and few there be that find it. In the case of organic evolution it is so straight and so narrow that any divergence therefrom is fatal to upward movement toward man. Once get off the track, and it is _impossible_ to get on again. No living form of animal is on its way _manward_, or can by any possibility develop into man. They are all gone out of the way. There is none going right; no, not one. The organic kingdom developing through all geological times may be compared to a tree whose trunk is deeply buried in the lowest strata, whose great limbs were separated in early geological times, whose secondary branches diverged in middle geological times, and whose extreme twiglets, and also its graceful foliage, its beautiful flowers, and luscious fruits, are the fauna and flora of the present day. But this tree of evolution is an _excurrent stem_, continuous through the clustering branches to the terminal shoot--man. Once leave the stem as a branch, and it is easy to continue growing in the direction chosen, but impossible to get back on the straight upward way to the highest. In human evolution, whether individual or racial, the same law holds, but with a difference. If individual or race gets off the straight, narrow way toward the highest--the divine ideal--it is hard, very hard to get back on the track. Hard, I say, but _not_ impossible, because man’s conscious voluntary effort is the chief factor in his own evolution. By virtue of self-activity, through the use of reason and co-operation in the work of evolution, man alone of all created things is able to rectify an error of direction and return again to the deserted way.