Stoic sexual ethics are grounded in their physics and cosmology. The 5th-century writer Macrobius preserves a Stoic interpretation of the myth of the birth of Venus as a result of the primal castration of the deity Heaven (Latin Caelus). The myth, Macrobius indicates, could be understood as an allegory of the doctrine of seminal reason. The elements derive from the "semina", "seeds," that are generated by heaven; "love" brings together the elements in the act of creation, like the sexual union of male and female. Cicero suggests that in Stoic allegory the severing of reproductive organs signifies, "...that the highest heavenly aether, that seed-fire which generates all things, did not require the equivalent of human genitals to proceed in its generative work".