A first principle is a premise-less syllogism valid if and only if it is impossible for its conclusion to be false. For example: All A is A (1, 2). There is no such thing as only one first principle, because that would result in being alone, acting alone, and/or meaning alone, each of which is an impossibility that collapses even if taken with just one of the others. The grand syllogism is premise-less and triadic.

There are three impossibilities, the opposites of which are the three first principles which are restatements of the triadic first principle:

The first impossibility is being alone.

Principle: Being alone cannot move or have a reason (why) to be.

The second impossibility is acting alone.

Principle: Action alone has no substance or reason (why) to move.

The third impossibility is meaning alone.

Principle: Reason (why) alone has no substance or action to inform.

Triadic first principle:
Being is substance with Action that moves with sustaining Reason (why).

1. Introduction to Logic, Harry J. Gensler, Routledge, 2002 (a 2005 reprint), p. 10.
2. Copilot’s take: Examples of First Principles