Boredom is... a vital problem for the moralist, since half the sins of mankind are caused by the fear of it.

Do not feel certain of anything.

A man who has once perceived, however temporarily and however briefly, what makes greatness of soul, can no longer be happy if he allows himself to be petty, self-seeking, troubled by trivial misfortunes, dreading what fate may have in store for him. The man capable of greatness of soul will open wide the windows of his mind, letting the winds blow freely upon it from every portion of the universe.

Man needs, for his happiness, not only the enjoyment of this or that, but hope and enterprise and change.

A process which led from the amoeba to man appeared to the philosophers to be obviously a progress though whether the amoeba would agree with this opinion is not known.

Understanding human nature must be the basis of any real improvement in human life. Science has done wonders in mastering the laws of the physical world, but our own nature is much less understood, as yet, than the nature of stars and electrons. When science learns to understand human nature, it will be able to bring a happiness into our lives which machines and the physical sciences have failed to create.

We shall say that we have acquaintance with anything of which we are directly aware, without the intermediary of any process of inference of any knowledge of truths.