There are books in which the footnotes, or the comments scrawled by some reader's hand in the margin, are more interesting than the text. The world is one of those books.

By "essence" I understand a universal, of any degree of complexity and definition, which may be given immediately, whether to sense or to thought.... This object of pure sense or pure thought, with no belief superadded, an object inwardly complete and individual, but without external relations or physical status, is what I call an essence.

Sanity is madness put to good use.

There is wisdom in turning as often as possible from the familiar to the unfamiliar: it keeps the mind nimble, it kills prejudice, and it fosters humor.

Uselessness is a fatal accusation to bring against any act which is done for its presumed utility, but those which are done for their own sake are their own justification.

An ideal cannot wait for its realization to prove its validity.

To understand oneself is the classic form of consolation; to elude oneself is the romantic.