That this is a picture within a picture only becomes apparent at a second glance through the black frame and red cord. This reflects a religious tradition, as images of the Virgin Mary and saints were, indeed, often decorated with flower garlands as a sign of reverence. Some flowers have a deeper meaning—the white lily stands for purity and, as such, for the Immaculate Conception.
Work on the painting was shared. At first, Rubens executed the image of the Virgin Mary and the putti; Brueghel then added the flowers.