The ontological implications of the Peircean Categories, as set forth most clearly in Peirce’s summative architectonic statement, “New Elements,” and referenced elsewhere in Peirce’s body of writings, are examined with reference to the existent or physical universe. The Peircean universal ontological Categories Firstness, Secondness, and Thirdness are shown to give rise to a cosmos that is triadic and representational in essence. This immanently representational cosmos, denominated the “Book Universe,” is shown to be evidenced by the representational contours of both the (...) mathematical and of the conceptual framing of the three broad domains of theoretical physics, the quantum, classical, and relativistic domains. This triadic “Book Universe” model is both characterized and also contrasted with the “Block Universe” model, and is seen to incorporate both time and space as emergent representational characteristics, and to be manifest, qua triadic Representamen, in terms of a “foliated eternalism” that requires both antecedent and parallel cosmoi. (shrink)