Aurora, goddess of dawn, fell in love with the mortal Cephalus and tried to seduce him. He thought only of his wife Procris and rejected her. Poussin shows the cause of Cephalus' rejection of Aurora through the putto holding up Procris' portrait, a detail not included in the best-known version of the story in Book 7 of Ovid's 'Metamorphoses'.
Aurora rises from the sea each day; hence the sleeping god is probably Oceanus. Her coming heralds the day; it is brought by Apollo, the sun god, driving his chariot. The figure to the left of the winged horse Pegasus may be Terra, a goddess associated with the beginning of the day.
The pose of Cephalus is similar to that of Bacchus in Titian's 'Bacchus and Ariadne', which was in Rome when Poussin was painting there. Oceanus is reminiscent of a figure by Agostino Carracci in the Farnese Palace frescoes in Rome which Poussin would have known.