Secrets of Mental Supremacy (Electronic book text)

The mind is one thing - a unit. All the various faculties act together constantly. One cannot remember what an oak tree looks like unless he has carefully observed an oak tree. He cannot imagine an oak tree unless he remembers it. He cannot judge of the difference between an oak tree and a maple tree unless he can imagine a picture of the two side by side. And he cannot do any one of these things without attention; nor again can he concentrate his attention without an act...