"Don't hit at all if it is honorably possible to avoid hitting; but never hit soft!"

"Spend and be spent."

"Put out the light."

"No man is justified in doing evil on the ground of expediency."

"Practical efficiency is common, and lofty idealism not uncommon; it is the combination which is necessary, and the combination is rare"

"If there is not the war, you don't get the great general; if there is not a great occasion, you don't get a great statesman; if Lincoln had lived in a time of peace, no one would have known his name."

"Science is but the statement of truth found out."

"Though boys throw stones at frogs in sport, the frogs do not die in sport, but in earnest."

"Never give advice... A wise man won't need it A fool won't heed it."

"This I do know beyond any reasonable doubt. Regardless of what you are doing, if you pump long enough, hard enough and enthusiastically enough, sooner or later the effort will bring forth the reward."

"I am an invisible man. No, I am not a spook like those who haunted Edgar Allan Poe; nor am I one of your Hollywood-movie ectoplasms. I am invisible, understand, simply because people refuse to see me."

"I myself am made entirely of flaws, stitched together with good intentions."