"Estrus" is derived via Latin "" ('frenzy', 'gadfly'), from Greek "oîstros" (literally 'gadfly', more figuratively 'frenzy', 'madness', among other meanings like 'breeze'). Specifically, this refers to the gadfly in Ancient Greek mythology that Hera sent to torment Io, who had been won in her heifer form by Zeus. Euripides used "oestrus" to indicate 'frenzy', and to describe madness. Homer used the word to describe panic. Plato also used it to refer to an irrational drive and to describe the soul "driven and drawn by the gadfly of desire". Somewhat more closely aligned to current meaning and usage of "estrus", Herodotus ("Histories", ch. 93.1) uses "oîstros" to describe the desire of fish to spawn.