People perceive me as a commodity. They just don't think anything of asking for five minutes of my time. It never occurs to them that if they're asking for it and another thousand people are asking, I don't have 1,000 five minutes to give.
Stephen Jay Gould
The plain man is familiar with blindness and deafness, and knows from his everyday experience that the look of things is influenced by his senses; but it never occurs to him to regard the whole world as the creation of his senses. Ernst Mach