"The scientist's greatest reward is the joy of discovery."

"An experiment is a question which science poses to Nature, and a measurement is the recording of Nature's answer."

"There is no matter as such! All matter originates and exists only by virtue of a force which brings the particle of an atom to vibration and holds this most minute solar system of the atom together. W…"

"The man who has had a spiritual awakening is a man of courage."

"The quantum of action, as I called it, was a purely formal assumption and I really did not think much about it."