My greatest personal mistake is ever to allow a word or moment that doesn't count, i.e., that I do not refer to my own basic principles. Every word, every action, every moment counts. (This is the pattern on which everybody makes mistakes [or] becomes irrational — not relating their one action or one conviction to another.

The Journals of Ayn Rand (ed. Penguin, 1999) - ISBN: 9781101137215