Book V of Eriugena’s Periphyseon presents new critical problems because of the lack of the Rheims manuscript, which contains the author’s own revisions. The text which has been called Versio Prima in the first four books of Jeauneau’s new edition is lacking for the fnal volume. Working from a transcription of the second portion of the Clauis Physicae, the epitome of the Periphyseon by Honorius Augustodunensis, the author reports that the unpublished Clauis II contains a text of Periphyseon V that (...) is analogous to Versio Prima. This article first compares the transcription from Clauis II to Lucentini’s notes on Honorius’ work, then it analyses the difference between Clauis II and Versio Secunda in Periphyseon V. The relationship is found to be the same as that between the primitive text of Periphyseon in books I-IV and Eriugena’s revised version . Consequently, Clauis II should be recognized as an essential witness to the early text of Periphyseon V. (shrink)