Its date is thus, to some extent, fixed for us. We cannot refer it to the days of Ambrose, and, since it is found in nearly all the twelfth to fourteenth-century breviaries, we are unable to attribute it to the period of the Renaissance. Its very verse would prevent this, if nothing else did. The word _spiritalis_ is a barbarism—an altogether post-classical expression. The true usage is that in which the genitive case is employed, thus “spiritual delight” would be _animi felicitas_, not _spiritalis_ (or _spiritualis_) _felicitas_. _Perpetim_ is also a word which purists of the new classic revival would avoid if they could. So, too, there is a certain amount of stress to be put upon the scanning of _Paraclitus_—where the _i_ is long, though Prudentius in the fifth century and Adam of St. Victor in the twelfth both make it short. It has therefore been said that the hymn was composed by a person who was skilled in the Greek language. This altogether depends on the question whether he pronounced the word by accent or by quantity. But still it is not to be denied that the prosody of the poet gives us reason to think that he did pronounce the word with the accent on the η. If this be so, it would follow that he was a man of rare and fine scholarship in comparison with the contemporaneous learning. Another criticism is purely theological and aids in fixing the date by the history of doctrine itself. At the Council of Toledo A.D. 589, the word _filioque_ was added to the Creed to indicate the faith of the Church in the procession of the Holy Spirit from both the Father and the Son. This hymn preserves this point of the orthodox belief with such care that there can be no doubt of its being subsequent in time to the date of that council. In coming more particularly to the various authors who have been credited with its composition, it may be well to attend to each claim as it is put forward in some sort of chronologic order. George Fabricius of Chemnitz (1564) was ready enough to ascribe it to Ambrose himself. The only ground for this conjecture is the structure of the verse. And this is no more a proof of authorship than that a hymn written in what we call “long metre” must be, because of that fact alone, the production of Isaac Watts. On the other hand, it is plain that the theological allusion and the doxology, when taken together, remove the hymn far enough away from the days of the great Bishop of Milan.