"As the circle of light increases, so does the circumference of darkness around it." -- Albert Einstein
"Vast is the field of science. The more a man knows, the more he will find he has to know."
-- Samuel Richardson (1689-1761), English novelist
"Well I am certainly wiser than this man. It is only too likely that neither of us has any knowledge to boast of; but he thinks that he knows something which he does not know, whereas I am quite conscious of my ignorance. At any rate it seems that I am wiser than he is to this small extent, that I do not think that I know what I do not know." -- Socrates (469–399 B.C.), quoted in Plato, Apology, sct. 19
"To know yet to think that one does not know is best; Not to know yet to think that one knows will lead to difficulty." -- Lao-Tzu (6th century B.C.), Tao-te-ching, bk. 2, ch. 71, trans. by T.C. Lau (1963).