Of Morality
Man has a single basic choice: to think or not, and that is the gauge of his virtue. Moral perfection is an unbreached rationality—not the degree of your intelligence, but the full and relentless use of your mind, not the extent of your knowledge, but the acceptance of reason as an absolute.
...the achievement of your happiness is the only moral purpose of your life, and that happiness—not pain or mindless self-indulgence—is the proof of your moral integrity, since it is the proof and the result of your loyalty to the achievement of your values.
Ayn Rand, Atlas Shrugged