Driven out by Agathocles, he migrated to Athens, where be studied rhetoric under a pupil of Isocrates and lived for fifty years. During the reign of Hiero II he returned to Sicily (probably to Syracuse), where he died.
While at Athens he completed his great historical work, The Histories, in more than 30 books, was divided into unequal sections, containing the history of Italy and Sicily in early times; of Sicily alone; of Sicily and Greece; of the cities and kings of Syria (unless the text of Suidas is corrupt); the lives of Agathocles and Pyrrhus, king of Epirus. The chronological sketch (The victors at Olympia) perhaps formed an appendix to the larger work.
Timaeus was bitterly attacked by other historians, especially by Polybius, and indeed his unfairness towards his predecessors, which gained him the nickname of Epitimaeus (fault-finder), laid him open to retaliation. Polybius was a practical soldier and statesman, Timaeus a bookworm without military experience or personal knowledge of the places he described. The most serious charge against Timaeus is that he wilfully distorted the truth, when influenced by personal considerations: thus, he was less than fair to Dionysius and Agathocles, while loud in praise of his favourite Timoleon.
On the other hand, as even Polybius admits, Timaeus consulted all available authorities and records. His attitude towards the myths, which he claims to, have preserved in their simple form (hence probably his nickname, Old Ragwoman, or "collector of old wives' tales", an allusion to his fondness for trivial details), is preferable to the rationalistic interpretation under which it had become the fashion to disguise them.
Timaeus also devoted much attention to chronology, and introduced the system of reckoning by Olympiads. This system, although not adopted in everyday life, was afterwards generally used by the Greek historians. Both Dionysius of Halicarnassus and the pseudo-Longinus characterized him as a model of "frigidity", although the latter admits that in other respects he is a competent writer.
Cicero, who was a diligent reader of Timaeus, expresses a far more favourable opinion, specially commending his copiousness of matter and variety of expression. Timaeus was one of the chief authorities used by Trogus Pompeius, Diodorus Siculus and Plutarch in his life of Timoleon.