One theory for this is that the Sun was among its stars in Midsummer . This was the time when the lions of the Egyptian desert left their usual home for the banks of the river Nile . One theory is that the Sun was among its stars in Midsummer , during which time the lions of the Egyptian desert left their accustomed haunts for the banks of the Nile , where they could find relief from the heat in the waters of the inundation .