The obvious reason for this exception is that it is the only one which contains a Gloria Patri in the middle of it.
We have already said that an ascription of Praise to the Holy Trinity is in this case more appropriate at the end of the first Stanza than at the end of the third, because the third Stanza has a prayerful character introduced into its words of praise.
The steps by which the doxology grew in Te Deum may be conjectured. The sentence which was required in the fifth line to complete the ascription of Praise to Christ would be an acknowledgement of His Sonship. For such an acknowledgement has not yet occurred. Using the words of the Hymn, we should expect
Te per orbem terrarum sancta confitetur ecclesia
Patris venerandum verum unigenitum Filium.
Here the Father and the Son are mentioned. The addition of the words
Sanctum quoque paracletum spiritum,
and of epithets to express the majesty of the Father {75} would complete the sentence and express the equality of the Persons.
Te per orbem sancta confitetur ecclesia
Patris immensae majestatis
Venerandum verum unigenitum filium,
Sanctum quoque paracletum spiritum.
But the two genitives, Patris, majestatis, suggest the accusative Patrem; and already the addition of Spiritum has suggested the inclusion, under Te, of the Three Persons.
[1] The word 'reward' is frequently to be found in the English Bible where the Vulgate has reddo.