This paper examines a conceptual model of the book advanced in the mid-20th century by the eminent Indian librarian and classification theorist S.R. Ranganathan (1892-1972), who formulated it with the aid of an ontological model drawn from Hindu philosophical thought. The analysis of this model, which has hitherto received only sporadic discussion in KO literature, unfolds in three parts. First, the paper outlines Ranganathan’s model, explains its Hindu philosophical background, and traces its development, showing that, in fact, it comprised two distinct versions – a triadic (i.e., three-entity) and a dyadic (i.e., two-entity) one – which were fully compatible to one another and which Ranganathan used in different contexts. Next, the structure of Ranganathan’s model, in both its triadic and dyadic forms, is compared with those of the contemporary bibliographic conceptual models most widely used today, IFLA-LRM (and its predecessor, FRBR) and BIBFRAME. It is shown that Ranganathan’s model bears some striking resemblances to these current models: in particular, the triadic version of Ranganathan’s model shares affinities with FRBR and IFLA-LRM, while the dyadic version is closer to BIBFRAME. Then follows a discussion of significant structural divergences between Ranganathan’s model and its latter-day counterparts, and an explanation for these differences is adduced. The paper concludes with a brief consideration of the surprising lack of historical connection between Ranganathan’s conceptual model of the book avant la lettre and current bibliographic conceptual models, as well as a reflection on the enduring relevance of Ranganathan’s model for today.