My Experience Is What I Attend To
Millions of items of the outward order are present to my senses which never properly enter into my experience. Why? Because they have no interest for me. My experience is what I agree to attend to. Only those items which I notice shape my mind — without selective interest, experience is an utter chaos. Interest alone gives accent and emphasis, light and shade, background and foreground — intelligible perspective, in a word. It varies in every creature, but without it the consciousness of every creature would be a gray chaotic indiscriminateness, impossible for us even to conceive.
The Principles of Psychology, volume II, p. 402f.