The subject of this picture comes from Ovid's 'Metamorphoses' (Books III and IV). Bacchus was the son of the god Jupiter and the mortal Semele. Jupiter's wife Juno brought about the death of Semele and Jupiter took the child from her womb and sewed it into his thigh, from where it was born. The infant Bacchus was watched over by Semele's sister Ino and Juno sought vengeance on Ino and her husband Athamas, but Venus transformed them into gods. Here, Bacchus' aunt Ino watches as he is held by his uncle Athamas.
The picture may be unfinished - this is particularly apparent in the areas of landscape to the left and right of the group of figures. It is related to a slightly earlier version (Paris, Louvre) of 1626-7 and, therefore, a date of 1628 is likely.