Euclid
Mathematician · fl. c. 300 BC · Mathematics, stage 3: Meet the mathematicians
Organised Greek geometry into a single deductive system and set the form mathematical writing has kept ever since.
Overview
Almost nothing is known about Euclid's life beyond that he worked in Alexandria around 300 BC. The Elements, thirteen books, opens with definitions, five postulates, and common notions, and then proves several hundred propositions in an order where nothing is used before it has been established. Most of the content was already known; the achievement is the arrangement, which made it possible to see exactly what each result depends on. Books VII to IX are about whole numbers rather than shapes and contain the proof that there are infinitely many primes and the algorithm for greatest common divisors that still carries his name. Start with Book I and read to Proposition 47, the theorem of Pythagoras, which is the first place the structure pays off visibly.
Where to start reading
Elements c. 300 BC
The founding text of deductive mathematics, covering plane geometry, proportion, number theory, and solid geometry. The Project Gutenberg edition is John Casey's version of the first six books, which is the part to read first.
Data c. 300 BC
A companion to the early books of the Elements, working out what else is determined once certain magnitudes in a figure are given.
