The decision of the Nicene council concerning Easter was that it should be computed independently of any Jewish computations: Christians were to compute their own, Christian, Nisan, and set Easter to its third Sunday, rather than setting it to the third Sunday in Jewish Nisan. Hence a paschalion that is consistent with Nicene principles cannot have any built-in dependence on the Hebrew calendar. Nevertheless, at least since the 12th century is it has been widely believed that Christian Easter is required always to follow, never coincide with, the first day of Unleavened Bread (Nisan 15) in the Hebrew calendar. By the 12th century the errors in the Julian calendar's equinox date and age of the moon had accumulated to where Easter did, in fact, always follow Jewish Nisan 15. This state of affairs continues to the present day, even though the Hebrew calendar suffers from a slight solar drift of its own, since the Julian calendar's errors accumulate more rapidly than the Hebrew calendar's. The 11th-12th century canonist [[Joannes Zonaras]] seems to have been the first to state the principle that Easter must always follow Hebrew Nisan 15. The principle is called the Zonaras proviso after him.