“The Bible says that lust in your heart is committing adultery, so you can't masturbate without lust.”

Interview in Playboy magazine (1976), while a candidate for President.
Pre-Presidency

Source: Dictionary of Burning Words of Brilliant Writers (1895), p. 348.

Source: Aeneid (29–19 BC), Book III, Lines 56–57 (tr. Robert Fagles); the murder of Polydorus.

The Ethics of Belief (1877), The Duty of Inquiry
Context: No man holding a strong belief on one side of a question, or even wishing to hold a belief on one side, can investigate it with such fairness and completeness as if he were really in doubt and unbiased; so that the existence of a belief not founded on fair inquiry unfits a man for the performance of this necessary duty.
Nor is it that truly a belief at all which has not some influence upon the actions of him who holds it. He who truly believes that which prompts him to an action has looked upon the action to lust after it, he has committed it already in his heart. If a belief is not realized immediately in open deeds, it is stored up for the guidance of the future. It goes to make a part of that aggregate of beliefs which is the link between sensation and action at every moment of all our lives, and which is so organized and compacted together that no part of it can be isolated from the rest, but every new addition modifies the structure of the whole. No real belief, however trifling and fragmentary it may seem, is ever truly insignificant; it prepares us to receive more of its like, confirms those which resembled it before, and weakens others; and so gradually it lays a stealthy train in our inmost thoughts, which may someday explode into overt action, and leave its stamp upon our character for ever.

Source: A Practical Guide to Samadhi (1957), p. 144

Ibn Shu’ba al-Harrani, Tuhaf al-'Uqul, p. 479
Religious Wisdom

Source: The Tenth Man

Source: Hawthorn and Lavender (1901), XXI
Context: Love, which is lust, is the Lamp in the Tomb.
Love, which is lust, is the Call from the Gloom.
Love, which is lust, is the Main of Desire.
Love, which is lust, is the Centric Fire.
So man and woman will keep their trust,
Till the very Springs of the Sea run dust.
Yea, each with the other will lose and win,
Till the very Sides of the Grave fall in.
For the strife of Love's the abysmal strife,
And the word of Love is the Word of Life.
And they that go with the Word unsaid,
Though they seem of the living, are damned and dead.