So we find a great department of psychology devoted to just this question--i.e., of tracing mind in the animals and in the child, and noting the stages of what is called its "evolution" in the ascending scale of animal life, and its "development" in the rapid growth which every child goes through in the nursery.

This gives us two chapters of the story of the mind.
Together they are called "Genetic Psychology," having two divisions, "Animal or Comparative Psychology" and "Child Psychology." 2.

Another general truth to note at the outset is this: that we are able to get real knowledge about the mind.

This may seem at first sight a useless question to raise, seeing that our minds are, in the thought of many, about the only things we are really sure of.

But that sort of sureness is not what science seeks.