I was taken aback the other day when I was reading the biblical reading from the Office of Readings and came across this passage: "Quoniam tres sunt, qui testimonium dant in cælo: Pater, Verbum, et Spiritus Sanctus: et hi tres unum sunt. Et tres sunt, qui testimonium dant in terra: spiritus, et aqua, et sanguis: et hi tres unum sunt" (1 John 5:7-8). I did not recall such an explicit mention of the Trinity in 1 John or anywhere in the Bible except Mt. 28. So, I looked in both the old and new NAB and found out that the Trinitarian text is not there! It says in the RNAB: "So there are three that testify, the Spirit, the water, and the blood, and the three are of one accord." In the Nova Vulgata it says: "Quia tres sunt, qui testificantur: Spiritus et aqua et sanguis; et hi tres in unum sunt." Clearly there was an alternative reading at the time of St. Jerome that later scholarship has interpreted as a gloss. Also, clearly my copy of the Latin office doesn't use the Nova Vulgata. The current critical edition of the Greek text (NA26) does not have the Trinitarian language. Since I don't have my copy at work I can't look up the footnotes.
Still, it is an amazing passage when read in the way St. Jerome did. I wish it were canonical, because then my task in teaching about the Trinity to seminarians would be easier!