Eudoxus of Cnidos (c. 408-355 BC) was a renowned mathematician and astronomer, who was briefly a student at Plato’s Academy in Athens. He also travelled to Egypt where he studied astronomy with the priests at Heliopolis(a).
He was one of the first to suggest that the ancient Egyptian use of lunar ‘years’ to measure time and so provided an explanation for the apparently exaggerated time spans given by their priests when describing the antiquity of their civilisation. This idea was subsequently echoed by Plutarch and Diodorus Siculus and later by Francisco Cervantes de Salazar in the 16th century. Spanuth and others have noted that the idea was reaffirmed in more recent times by Egypt’s former King Farouk.
It is probably appropriate that a lunar crater has been named after him.