My favorites (on first reading):
There is assuredly no more effectual method of clearing up one's own mind on any subject than by talking it over so to speak, with men of real power and grasp, who have considered it from a totally different point of view.
Of all the senseless babble I have ever had the occasion to read, the demonstrations of these philosophers who undertake to tell us all about the nature of God would be the worst, if they were not surpassed by the still greater absurdities of the philosophers who try to prove that there is no God.
History warns us that it is the customary fate of new truths to begin as heresies and to end as superstitions.
The most considerable difference I note among men is not in their readiness to fall into error, but in their readiness to acknowledge these inevitable lapses.
It is one of the most saddening things in life that, try as we may, we can never be certain of making people happy, whereas we can almost always be certain of making them unhappy.