Caerus is the due measure that achieves the aim. This god brings about what is convenient, fit, and comes in the right moment. Sometimes it could be the critical or dangerous moment, but more often Caerus represents the advantageous, or favorable occasion. Hence, what is opportune, or "Opportunity". In the Hellenistic age, the term was also used as "time" or "season".

According to Pausanias, there was an altar of Caerus close to the entrance to the stadium at Olympia, for Opportunity is regarded as a divinity and not as a mere allegory. This indefatigable traveller also tells us that Caerus was regarded as the youngest child of Zeus in a hymn by Ion of Chios.

Caerus is represented as a young and beautiful god. Opportunity obviously never gets old, and beauty is always opportune, flourishing in its own season. Caerus stands on tiptoe because he is always running, and like Hermes, he has wings in his feet to fly with the wind. He holds a razor, or else scales balanced on a sharp edge—attributes illustrating the fleeting instant in which occasions appear and disappear.

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