We must notice that the Psalmody took place daily in this way, while the Mass, especially in the East, was not celebrated daily; in Lent, for example, it was celebrated on Saturdays and Sundays only. At each hour there took place a dismissal, _missa_, and thus it was brought about that this word came to be used as a name for each of the canonical hours. The name was far-fetched and unsuitable, but popular usage does not form its nomenclature upon scientific principles, but from what most strikes the popular fancy. Thus the pilgrim, who expresses herself in popular language, speaks of _missa vigiliarum_, for Mattins, and _missa lucernaris_ for Vespers. The word _missa_ in itself means dismissal and nothing more. Once, in her naïve manner, she explains what sort of dismissal she means; it is dismissal out of the church (“_missa de ecclesia_,” c. 37, § 3, line 20). Which of the various dismissals out of the church is intended in a given case is shown by an additional phrase, as in the cases given above, when it is not clear from the context. Of course it may mean the dismissal which took place at the Mass, but not the sacrifice of the Mass itself. How far _missa_ is from being in the pilgrim’s diary the technical term for Mass—which is all we are concerned with here—is sufficiently clear from the circumstance that wherever she lets slip the word _missa_ for Mass, she at once hastens to add that the _missa_ of which she speaks is the _oblatio_.[850] When she wishes to express herself with precision, she always calls the Mass _oblatio_, and in a few cases _sacramentum_ (singular or plural). Of course _missa_, as a general term, may have been used as a name for the Mass, since there are one or more dismissals therein; had it not been so, _missa_ could never have become the name _par excellence_ for the Mass. The same terminology is found at a somewhat later date in Cassian, to whom we are especially indebted for our intimate knowledge of monastic observances. An important part of these observances were the daily hours of prayer, the canonical hours, and we naturally expect to find the technical terms for them in Cassian’s writings. And so, indeed, we find the names formed with the help of the word _missa_, as in Silvia’s diary; Mattins and Lauds are called _missa nocturna_ or _missa vigiliarum_,[851] while the Mass, on the other hand, is called _oblatio_ or _sacrificium_.