Varro (Fragments, p. 219, Scaliger's edition, 1623) recognises three ages:—
From the beginning of mankind to the Deluge, a time wholly unknown.
From the Deluge to the First Olympiad, called the mythical period.
From the first olympiad to the present time, called the historic period.
Titian symbolised the three ages of man thus:—
An infant in a cradle.
A shepherd playing a flute.
An old man meditating on two skulls.
According to Lucretius also, there are three ages, distinguished by the materials employed in implements (v. 1282), viz.:—
The age of stone, when celts or implements of stone were employed.
The age of bronze, when implements were made of copper or brass.
The age of iron, when implements were made of iron, as at present.
Hesiod names five ages, viz.:—
The present is sometimes called the wire age, from its telegraphs, by means of which well-nigh the whole earth is in intercommunication.
Fichte names five ages also: the ante-diluvian, post-diluvian, Christian, satanic, and millennian.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894