first principle

"First principles" are fundamental, self-evident truths. In philosophy, particularly Aristotelian thought, "First Philosophy" refers to the study of being itself, its fundamental causes, and supersensible, immutable being, often equated with metaphysics.12

The earliest Greek philosophers, known as cosmologists or naturalists, sought to explain the origin of the world through natural, rather than mythological, means. Thales of Miletus, considered the first Greek philosopher, proposed that water was the origin of all things. His successors, Anaximander and Anaximenes, further developed these ideas, suggesting an indefinite substance (apeiron) and air, respectively, as the fundamental principle (arche) from which all things arise through processes like condensation and rarefaction. This concept of an unchanging principle underlying transformations laid groundwork for later scientific conservation laws.34