Natural selection is not the wind which propels the vessel, but the rudder which, by friction, now on this side and now on that, shapes the course.

The best opinion now is, that there are multitudinous forms which are not sufficiently differentiated to be distinctively either plant or animal, while, as respects ordinary plants and animals, the difficulty of laying down a definition has become far greater than ever before.

It was always understood that plants and animals, though completely contrasted in their higher representatives, approached each other very closely in their lower and simpler forms. But they were believed not to blend.

It remains to consider what attitude thoughtful men and Christian believers should take respecting them, and how they stand related to beliefs of another order.

Faith in order, which is the basis of science, cannot reasonably be separated from faith in an Ordainer, which is the basis of religion.

Your candor is worth everything to your cause. It is refreshing to find a person with a new theory who frankly confesses that he finds difficulties, insurmountable, at least for the present.

The former conviction that these two kingdoms were wholly different in structure, in function, and in kind of life, was not seriously disturbed by the difficulties which the naturalist encountered when he undertook to define them.