“The man who never alters his opinions is like standing water, and breeds reptiles of the mind”

“Who knows, the mind has the key to all things besides”

“One must be a wise reader to quote wisely and well”

“The investigation of the meaning of words is the beginning of education”

“Not to unlearn what you have learned is the most necessary kind of learning.”

“It is well for people who think to change their minds occasionally in order to keep them clean. For those who do not think, it is best to at least rearrange their prejudices once in a while”