THE PRINCIPLE OF INTERCALATION ON the 28th of Ellul the sun and the moon were created. The number of years, months, days, nights, terms, seasons, cycles, and intercalation were before the Holy One, blessed be He, and He intercalated the years and afterwards He delivered the (calculations) to the first man in the garden of Eden, as it is said, "This is the calculation for the generations of Adam" (Gen. 5:1), the calculation of the world is therein for the generations of the children of Adam.