There was things which he stretched, but mainly he told the truth. — Mark Twain

"Honesty is the best policy — when there is money in it."

"He says every man is a moon and has a side which he turns toward nobody: you have to slip around behind if you want to see it.Google Books link"

"There is nothing in the world like a persuasive speech to fuddle the mental apparatus and upset the convictions and debauch the emotions of an audience not practised in the tricks and delusions of oratory."

"A round man cannot be expected to fit in a square hole right away. He must have time to modify his shape."

"Always do right. This will gratify some people, and astonish the rest."

"A powerful agent is the right word. Whenever we come upon one of those intensely right words in a book or a newspaper the resulting effect is physical as well as spiritual, and electrically prompt."