There is a collective as well as an individual humor inclining peoples to sadness or cheerfulness, making them see things in bright or somber lights. In fact, only society can pass a collective opinion on the value of human life; for this the individual is incompetent.

Even one well-made observation will be enough in many cases, just as one well-constructed experiment often suffices for the establishment of a law.

To pursue a goal which is by definition unattainable is to condemn oneself to a state of perpetual unhappiness.

That men have an interest in knowing the world which surrounds them, and consequently that their reflection should have been applied to it at an early date, is something that everyone will readily admit.

A monomaniac is a sick person whose mentality is perfectly healthy in all respects but one; he has a single flaw, clearly localized. At times, for example, he has an unreasonable and absurd desire to drink or steal or use abusive language; but all his other acts and all his other thoughts are strictly correct.

Man cannot become attached to higher aims and submit to a rule if he sees nothing above him to which he belongs. To free him from all social pressure is to abandon him to himself and demoralize him.

Man could not live if he were entirely impervious to sadness. Many sorrows can be endured only by being embraced, and the pleasure taken in them naturally has a somewhat melancholy character.