Principle

(prĭn'sĭ-pl), n. [Fr. principe, It. & Sp. principio, Lat. principium, from princeps, principis. See PRINCE.]

1. Beginning; commencement. [Obs. and rare.] “Doubting sad end of principle unsound.” Spenser.
2. Hence, a source, or origin; that from which any thing proceeds; fundamental substance or energy; primordial substance or indecomposable element.

The soul of man is an active principle. Tillotson. 3. An original faculty or endowment of the soul. Under this title are comprehended all those active principles whose direct and ultimate object is the communication either of enjoyment or suffering to any of our fellow-creatures. D. Stewart. 4. A fundamental truth or tenet; a comprehensive law or doctrine, from which others are derived, or on which others are founded; an elementary proposition; a maxim, axiom, or postulate. A good principle, not rightly understood, may prove as hurtful as a bad. Milton. 5. A settled rule of action; a governing law of conduct; an opinion or belief which exercises a directing influence on the life and behavior; usually, a right rule of conduct; correct opinion consistently directing one's actions. All kinds of dishonesty destroy our pretenses to an honest principle of mind. Law. 6. (Chem.) An original element which characterizes some substance, and from which it may be obtained by the process of analysis. Cathartine is the bitter, purgative principle of senna. Gregory. Proximate principle. See PROXIMATE.