The Greeks themselves had at first two, not three, Horae. In early days it is not realized that the Seasons, and with them the food-supply, depend on the Sun. The Seasons, the Horae, are potencies, divinities in themselves, and there are but two Seasons, the fruitful and the fruitless.
Harrison argues that the Horae were originally dual potencies rooted in agrarian experience, not abstractions of time, and that their proliferation to three and four tracks evolving cosmological awareness.
, Themis: A Study of the Social Origins of Greek Religion, 1912thesis