Castor and Pollux horse breaker and the boxer / Polydeuces, my brothers" ..." – Helen, "Iliad" 3.253–255), but in the "Odyssey" they are treated as alive even though "the corn-bearing earth holds them". The author describes them as "having honour equal to gods", living on alternate days because of the intervention of Zeus. In both the "Odyssey" and in Hesiod, they are described as the sons of Tyndareus and Leda. In Pindar, Pollux is the son of Zeus while Castor is the son of the mortal Tyndareus. The theme of ambiguous parentage is not unique to Castor and Pollux; similar characterisations appear in
Leda and the Swan (Correggio) and extraordinary balance between naturalist rendering and poetic transfiguration. Correggio had made a study of Michelangelo's "Leda and the Swan". According to Vasari's "Lives of the Artists", the "Leda" and a "Venus" (i.e. "Danaë") were commissioned by Federico II Gonzaga, Duke of Mantua as a gift for Charles V, Holy Roman Emperor. This is supported by the theory that Jupiter was flying out of the right hand side of "Leda" in swan form and into the left hand side of "Danaë" in golden-shower form. However, one more recent study suggests that all the paintings in the "amori di Giove" series