Indeed, the garment of the Word is visible creation, which preaches Him openly and manifests His beauty to us. The Holy Scriptures have also been made His garment, which contains the mysteries.
(Commentarius in Sanctum Evangelium secundum Johannem I, xxix)
Eriugena distinguishes between the Incarnation of the Logos (Word) in Jesus, "by which He joined human nature to Himself in a unity of substance" and the quasi-incarnation of the Logos by which He is "rendered thick" and "visible" in both creation and Scripture.
So the Logos is "incarnate"
- in creation,
- in Scripture,
- but most supremely in Jesus.
For Eriugena, in order to stress the uniqueness of Jesus, the word "incarnation" is reserved for the final mode. The other modes are quasi incarnatum. (Eriugena also rightly consider the deification of human beings in the eschaton to be a quasi-incarnation of the Logos.)
Still, again we find this interesting metaphor of God revealed indirectly in the shape of his garments. So the garment image predates Thomas Carlyle. Indeed, I think that it predates Eriugena, who was commenting on Maximus the Confessor. I'll need to check that out.