It's Complicated*

One must realize that the second most complicated thing in the world is a human being, and that the most complicated is a group of them.

This is an axiom, or maxim, I use often in my work with executives and students.

Axiom: In traditional logic, an axiom or postulate is a proposition that is not proved or demonstrated but considered to be self-evident. Therefore, its truth is taken for granted, and serves as a starting point for deducing and inferring other (theory dependent) truths.

Maxim: The succinct formulation of an ultimate truth, a fundamental principle, or a rule of conduct. The word derives from the Latin word maximus, "greatest", via an expression maxima propositio, "greatest premise".