Eudoxus of Cnidus (c.408 - c.355 BC) was one of the greatest Greek mathematicians. He was also an astronomer, philosopher and legislator.

His main contributions to mathematics were:

• the theory of proportion, which resolved the crisis in Greek mathematics caused by the discovery of irrational numbers;
• the method of exhaustion, which was a precursor (by 2000 years) of the integral calculus.

He may also have been responsible for the development of the axiomatic method, the foundation of modern mathematics.

His work in astronomy has stood the test of time less well. He developed a model of the universe which sought to explain the motions of the sun, the moon and the planets by fixing them to a system of 27 (or according to some authorities, 55) concentric spheres. These rotated on assorted axes at various speeds with the earth at the centre. Even with all this ingenuity he was unable to explain the motions of Venus and Mars nor the variation in brightness of the moon. His scheme was a magnificent attempt to explain observed phenomena, but wrong.

More long lasting in its influence was 'the sphere of Eudoxus'. This was an engraved celestial globe which showed the constellations together with their names. Eudoxus did not invent these, but carried them over from an earlier civilisation, most probably the Babylonians of c. 2500 BC. These names have remained in use to this day and are also the names we use as the signs of the Zodiac.

Further information about Eudoxus can be found in his mathematical biography.

Eudoxus (Eudoxos) is Greek for "of good repute".