A proposed system of regulating the sequence of the year in closer consistency with Christian feasts and seasons. The Second Vatican Council declared itself not opposed to assigning Easter to a fixed date in the Gregorian calendar, the one now popularly used in the Western world. Presently, Easter falls on the Sunday following the full moon after the vernal equinox, and it varies in date. As a result the period of Lent, together with the feasts of Pentecost, Ascension, and many others, also vary each year. This stabilization, however, is to depend on acceptance by other Christians. Furthermore, the Council declared that it would not oppose a perpetual calendar that retains a seven-day week with Sunday, without the introduction of any days outside the week, so that the succession of weeks remains intact. All of this presumes that there are no very grave reasons against the proposed change.