The effect of this letter is not known, but there is no doubt that during the twelfth century the feast made steady progress in France. Unfortunately we possess only a few data to illustrate its development, for the investigation into the ecclesiastical history of special localities requires to be more extensively taken in hand. In Rouen, the capital of Normandy, it was certainly observed at that period, as we have already seen. Next, its observance is prescribed by the statutes of Le Mans, in the Province of Tours, in 1247.[552] In Rheims it appears between 1261-1271. A more important fact is that the General Chapter of the Franciscans, held at Pisa in 1263, decreed that the feast should be celebrated throughout the entire order.[553] Although it did not attain to the rank of a feast of obligation for clergy and people, yet it became known throughout the world, and especially at the papal Court at Avignon, where Franciscan influence was strong. Finally the standpoint of the thirteenth century with regard to this feast is best summed up in the words of St Thomas Aquinas, “Although the Roman Church does not celebrate it, she allows other Churches to do so,”[554] and in those of St Bonaventure who justifies the keeping of a festival on the day of our Lady’s conception.[555] Accordingly the number of dioceses and provinces within which it was celebrated was constantly on the increase; for the fourteenth century we have Canterbury 1328; Treves between 1338 and 1343;[556] Paderborn 1343; Münster 1350;[557] Utrecht 1350; Brixen 1399, while other diocesan synods, _e.g._ Prague in 1355, did not yet adopt it. When it is asserted that the feast had been introduced at Liège under Bishop Albero II. († 1145), it must be urged on the other side that the list of feasts drawn up by the diocesan synod of Liège in 1287 makes no mention of it.[558] The synod of Cologne of 1308 does not mention it either, although it is contained in the Cologne Calendar of the same century. For Mainz we have the fact that this feast is employed for dating a decree of the year 1318.[559] In the province of Canterbury, the feast obtained official recognition only in 1328, _i.e._ two hundred and nineteen years after the death of those who had first exerted themselves in its favour.[560]