"What goes up must come down."

"The whole difficulty of philosophy seems to consist in this—from the phenomena of motions to investigate the forces of nature, and then from these forces to demonstrate the other phenomena."

"I do not know what I may appear to the world, but to myself I seem to have been only like a boy playing on the seashore, and diverting myself in now and then finding a smoother pebble or a prettier sh…"

"For if the experiments which I relate be accurate, the science of colours will be a new one; for although colours have been observed from antiquity, yet the cause of their productions has remained unk…"

"It is not the business of philosophy to account for the truth of things by hypotheses, but to deduce them from phenomena."