Cherub with Hourglass
A winged child holds an hourglass over a pair of birds. The hourglass usually represents the passing of time or mortality. The hourglass is has two snakes entwined around it. Sometimes snakes are used symbolically to represent eternity (since they can make a loop) or the cheating of death (it was commonly believed that snakes revitalized themselves by shedding their skin).
The Poetical Works of Henry Wadsworth Longfellow (New York, NY: Houghton, Mifflin and Company, 1899) 490