Joseph M. Bachelor, The Century Vocabulary Builder
“ Concrete Terms; General vs. Specific Terms>Abstract terms convey ideas; concrete terms call up pictures. If we say "Honesty is the best policy," we speak abstractly. Nobody can see or hear or touch the thing honesty or the thing policy; the apprehension of them must be purely intellectual. But if we say "The rat began to gnaw the rope," we speak concretely. Rat, gnaw, and rope are tangible, perceptible things; the words bring to us visions of particular objects and actions. ”
