With the fact that the heathen worship of Rome recognised three sorts of such _feriæ_ observed thrice in the year (no evidence of a fourth being forthcoming), agrees a passage in the _Liber Pontificalis_, which has long been regarded as the earliest evidence for the observance of Embertides, though it fell short of absolute proof. The passage states that Calixtus (217-222) ordained a fast on three Saturdays in the year.[406] The number corresponds well with the three sets of heathen _feriæ_ mentioned above. As St Leo speaks of four fasts of this kind yearly in the fifth century, the fourth fast, corresponding to the fourfold division of the year, must have been added in the course of the fourth century. It may be that the passage, Zacharias viii. 19, referring to a Jewish custom of sanctifying by a fast the four seasons of the year, helped to bring this about. All four Embertides are mentioned in the sermon of Leo the Great, and both the Leonine and Gelasian sacramentaries agree in marking Wednesday, Friday, and Saturday as the days to be observed as fasts.[407] Pope Gelasius[408] appointed that ordinations of priests and deacons were to be held on all Embertides, and in the middle of Lent, whereas in St Leo’s time the ordination of priests took place at Easter only.[409] The Ember fasts were called _jejunium primi, quarti, septimi et decimi mensis_, in the earliest service-books, and fell in March, June, September, and December. The week in each of the aforesaid months, in which the Ember fast was to be observed, appears not to have been definitely fixed in earlier days. If the opinion of Morin is correct, this would agree with the fact that the harvest feast was not fixed for any day in particular, but was determined by the pontiffs in each case. However, it remained for a long period undetermined whether the first Embertide should be observed before or during the course of Lent, and also in which week of Advent the last Embertide should fall. The present arrangement, according to the Micrologus[410] was first made by Gregory VII., _i.e._, the first Embertide to fall in the first week of Lent, the second in Whitsun week, the third in the third week of September, the fourth in the third week in Advent.