Temperance is identified in Western art by two vessels, one being poured into the other. The gesture is the mixing of water with wine, which is what moderation looked like at a Roman or a medieval table, and it is the single most reliable attribute in the whole virtue repertoire: a figure pouring one jug into another is temperance in almost any programme, from a cathedral portal to a tarot trump.
She acquired a second and stranger attribute in the later Middle Ages. From the fourteenth century onward, painters began to give temperance a mechanical clock, along with spectacles, a bridle and a windmill: objects of regulation and measure. The historian Lynn White drew attention to this, arguing that the clock enters moral iconography at the moment the escapement enters European life, and that a society learning to keep hours reached for the machine as its emblem of self government. The bridle survives in the same logic; Giotto's temperance at Padua is bound and bridled rather than pouring.
The tarot trump named Temperance carries the vessels rather than the clock, which is one of several places where the trump sequence preserves the older layer of the iconography.
Temperance is the virtue that appears in both virtue schemes treated in this collection, standing against gluttony among the contraries and holding a place among the four cardinal virtues, and the vessels serve in either. The atlas draws her emblem accordingly.