Working from this rounded-up figure, the Osiris myth is capable of yielding a value of 2160 years for a precessional shift through one complete house of the zodiac. The correct figure, according to today’s calculations, is 2148 years.10 The Hipparchus figures are 2400 years and 2347.8 years respectively. Finally, Osiris enables us to calculate 25,920 as the number of years required for the fulfilment of a complete precessional cycle through 12 houses of the zodiac. Hipparchus gives us either 28,800 or 28,173.6 years. The correct figure, by today’s estimates, is 25,776 years.11 The Hipparchus calculations for the Great Return are therefore around 3000 years out of kilter. The Osiris calculations miss the true figure by only 144 years, and may well do so because the narrative context forced a rounding-up of the base number from the correct value of 71.6 to a more workable figure of 72.