We owe almost all our knowledge not to those who have agreed, but to those who have differed

Memory is the friend of wit, but the treacherous ally of invention; there are many books that owe their success to two things; good memory of those who write them, and the bad memory of those who read them

Mystery is not profoundness

Knowledge is two-fold, and consists not only in an affirmation of what is true, but in the negation of that which is false.

That writer does the most who gives his reader the most knowledge and takes from him the least time

None are so fond of secrets as those who do not mean to keep them; such persons covet secrets as a spendthrift covets money, for the purpose of circulation