Four Major Feasts. Presumably the Annunciation, the Visitation, Assumption, and Nativity of Our Lady are intended. Candlemas, which in the Middle Ages had an octave in many dioceses, may be intended instead of the Visitiation. The last Pope, Sixtus IV, had in 1470 published a work on the Immaculate Conception. By a decree of 28 February, 1476, this Pontiff adopted the Feast of Our Lady's Conception for the entire Latin Church and granted an indulgence to all who should assist at the Divine Office of this Solemnity.