32.
The celebration of Easter and Pentecost is therefore most firmly based on Scripture. As to the observance of the forty days before Easter, this has been confirmed by the practice of the Church; as also the separation of the eight days of the neophytes, in such order that the eighth of these coincides with the first. The custom of singing the Alleluia on those 50 days only in the Church is not universal; for in other places it is sung also at various other times, but on these days it is sung everywhere. Whether the custom of standing at prayer on these days and on all the Lord's days, is everywhere observed or not, I do not know; nevertheless, I have told you what guides the Church in this usage, and it is in my opinion sufficiently obvious. 1
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He refers to the significance of the standing upright as an emblem of resurrection. ↩