Moses at the left, with the hooded Eleazar beside him, calls to the people of Israel who are being attacked by a plague of serpents that God sent them because of their sinfulness. He tells them to look at a bronze serpent he has set up on a pole, upper left, because 'everyone that is bitten, when he looketh upon it shall live.' Old Testament (Numbers 21: 6-9).
This work was probably executed with some studio assistance during the second half of the 1630s. The painting may have been blocked in by a member of the studio on the basis of a modello by Rubens, and then worked up by the master.
It has been suggested that the woman at the right of centre in black may be based on the artist's second wife Hélène Fourment.