Who said “What is called an acute knowledge of human nature is mostly nothing but the observer's…”?

“It is not human nature we should accuse but the despicable conventions that pervert it.”

“There seems to be some perverse human characteristic that likes to make easy things difficult.”

“The only thing that one really knows about human nature is that it changes. Change is the one quality we can predicate of it. The systems that fail are those that rely on the permanency of human nature, and not on its growth and development. The error of Louis XIV was that he thought human nature would always be the same. The result of his error was the French Revolution. It was an admirable result.”

“Human nature is not of itself vicious.”

“There is a great deal of human nature in people.”

“Ideas too are a life and a world.”

“Virtue by premeditation isn't worth much.”

“First we have to believe, and then we believe.”

“Man is to be found in reason, God in the passions.”

“Erudition can produce foliage without bearing fruit.”

“Once we know our weaknesses they cease to do us any harm.”