By this term is understood truths or propositions so clear that they cannot be proved nor contradicted, unless by propositions which are still clearer.
They are of two kinds, one when the principle is universal, and these are known as axioms or maxims; as, no one can transmit rights which he has not; the accessory follows the principal, etc.
The other class are simply called first principles. These principles have known marks by which they may always be recognized. These are, 1. That they are so clear that they cannot be proved by anterior and more manifest truths. 2, That they are almost universally received. 3. That they are so strongly impressed on our minds that we conform ourselves to them, whatever may be our avowed opinions.
First principles have their source in the sentiment of our own existence, and that which is in the nature of things. A principle of law is a rule or axiom which is founded in the nature of the subject, and it exists before it is expressed in the form of a rule. The right to defend one's self, continues as long as an unjust attack, was a principle before it was ever decides by a court, so that a court does Dot establish but recognize principles of law.
In physics, by principle is understood that which constitutes the essence of a body, or its constituent parts. Taken in this sense, a principle cannot be patented; but when by the principle of a machine is meant the modus operandi, the peculiar device or manner of producing any given effect, the application of the principle may be patented.