MATHEMATICIAN, ASTRONOMER

Life
Most of what we know about Xenocrates comes from a biography by Diogenes Laertius. He was born in Chalcedon, and was among Plato's first pupils. He succeeded Speusippus as head of the Academy, and continued as its head for 25 years (from 339 until his death in 314). With Plato and Speusippus he travelled to Syracuse, to visit the Pythagoreans of Magna Graecia (south Italy). After Plato's death, he left Athens with Aristotle; they travelled to Assos (on the coast of Asia Minor, near Troy), where they debated with the Platonists Erastus and Coriscus. Xenocrates prepared the works of Plato for publication by the Academy. According to Iamblichus, he "delved deep into the dialogues of Plato, and the writings of Philolaus". Xenocrates ascribed particular importance to mathematics, and wrote many treatises on mathematics and astronomy. He solved the problem of combinatorial analysis, finding for example, that the number of syllables that can be written with the letters of the Greek alphabet is 1,002,000,000,000.


Work
Xenocrates' writings are lost except for fragments. He is cited by Stobaeus; and Diogenes Laertius, in his biography, provides the following list of his works:

"On logic": 9 books.

"On mathematics": 6 books.

"On the theory of numbers"

"On intervals"

"On astrology": 6 books.

"On geometry": 5 books. History of geometry.

"On the teachings of Pythagoras"

"On learning"

"On physics": 6 books.