背诵6-Euclid's Goemetry

The most developed of Greek sciences was geometry. Euclid's work was done after Aristotle's death, but Euclid himself built on the researches of his predecessors, and those predecessors had given at least some thought to what was to become the distinctive feature of Euclid's own geometrical science. In a word, Euclid's geometry is an axiomatised system: he selects a few simple principles, or axioms, which he posits as the primary truths of his subject; and from those axioms he derives, by a series of logically compelling deductions, all the other truths of geometry. Geometry thus consists of derived truths, or theorems, and primary truths, or axioms. Each theorem follows logically - though often by way of a long and complex chain of reasoning -- from one or more of the axioms.