Plato

“The art of being wise is knowing what to overlook.”
― William James

“All hope abandon, ye who enter here.”
― Dante Alighieri, The Divine Comedy: Inferno - Purgatorio - Paradiso

“The greatest discovery of any generation is that a human can alter his life by altering his attitude.”
― William James

“Upon this first, and in one sense this sole, rule of reason, that in order to learn you must desire to learn, and in so desiring not be satisfied with what you already incline to think, there follows one corollary which itself deserves to be inscribed upon every wall of the city of philosophy: Do not block the way of inquiry.”
― Charles S. Peirce