But whether true or false, my opinion is that in the world of knowledge, the realm of "the Good" appears last of all and is seen only with an effort. And, when seen, it is also understood to be the universal Cause of all things beautiful and right, Father of 'light and Lord of light in this visible world, and the immediate Source of reason and truth in the intelligible world; and to be the Power on which he who would act rationally either in public or private life must have his eye fixed." "I agree," said Glaucon, "as far as I can understand you."

(Plato)