Jacopo Comin, "Robusti" (Venice 1518 - 1594), known as "Tintoretto" because he was the son of a silk dyer, is, together with Titian, the great Venetian master of the Renaissance.
The canvas depicted on this stamp is in the National Gallery, London.
It alludes to the Greek myth about the origin of the Milky Way: Heracles (Roman Hercules), the love child of Zeus (Roman Jupiter) and a mortal, Alcmene, is taken at 8 months of age to suckle the goddess Hera (Roman Juno, wife of Zeus-Jupiter) while she sleeps, in order to make him an immortal god; Hera wakes with a start, pushes him away and a jet of milk escapes into the firmament, creating the Milky Way (needless to say, Hera had already tried to kill the bastard son of her unfaithful husband).