“The fourfold root of the principle of sufficent reason is "Anything perceived has a cause. All conclusions have premises. All effects have causes. All actions have motives.”

“The true basis and propaedeutic for all knowledge of human nature is the persuasion that a man's actions are, essentially and as a whole, not directed by his reason and its designs; so that no one becomes this or that because he wants to, though he want to never so much, but that his conduct proceeds from his inborn and inalterable character, is narrowly and in particulars determined by motivation, and is thus necessarily the product of these two factors.”

“It may sometimes happen that a truth, an insight, which you have slowly and laboriously puzzled out by thinking for yourself could have easily have been found already written in a book: but it is a hundred times more valuable if you have arrived at it by thinking for yourself. For only then will it enter your thought system as an integral part and living member, be perfectly and firmly consistent with it and in accord with all its other consequences and conclusions, bear the hue, colour and stamp of your whole manner of thinking, and have arrived at just the moment it was needed ; thus it will stay firmly and forever lodged in your mind.”

“Small causes can often have large effects. Smaller causes can have even bigger effects, and the very biggest effects frequently have no cause at all. Witness, for example, the world. It was created out of nothing, and that has made it the worst calamity the world has ever seen.”

“It often happens that we blurt out things that may in some kind of way be harmful to us, but we are silent about things that may make us look ridiculous; because in this case effect follows very quickly on cause.”

“All human actions have one or more of these seven causes: chance, nature, compulsion, habit, reason, passion, and desire.”

“But it is common knowledge that religions don’t want conviction, on the basis of reasons, but faith, on the basis of revelation. And the capacity for faith is at its strongest in childhood: which is why religions apply themselves before all else to getting these tender years into their possession. It is in this way, even more than by threats and stories of miracles, that the doctrines of faith strike roots: for if, in earliest childhood, a man has certain principles and doctrines repeatedly recited to him with abnormal solemnity and with an air of supreme earnestness such as he has never before beheld, and at the same time the possibility of doubt is never so much as touched on, or if it is only in order to describe it as the first step towards eternal perdition, then the impression produced will be so profound that in almost every case the man will be almost incapable of doubting this doctrine as of doubting his own existence, so that hardly one in a thousand will then possess the firmness of mind seriously and honestly to ask himself: is this true?”