Francastel in this book tries to construct a relay, a deep common ground, between the aesthetic and the technological. His methodology is roughly a sociological or even anthropological one. By means of anthropological analysis he tries to single out the concordance that supervenes the two - the aesthetic and the technological. However, his focus, his aim, is towards a much deeper level of confluence: a complete re-evaluation of the schema of categorization that generates the segragation between the aesthetic and the technological, between fine art and architecture and technology. Hence what he's actually trying to do is a:

[...] (metaphysical-theological restructuring) or in a complete reformulation of the categories which originated in, roughly speaking, the 12th centuries, e.g. in the work of St.Bonaventure (De Redcutione Artium ad Theologiam), that may possibly in a structural manner resolve the tension that maintains the cleavage [...]

(See (Preface to) an Intellectual Grasp of the Meaningfulness of Art)

His investigation is incomplete and only gives a faint idea of the direction that one should take in order to initiate an all-encompassing project, but a feeling, an intuition, should slowly emerge, as to a kind of future metaphysics that in its shapes takes the form of a sort of "structural regulation principle" that fully incorporates the pivotal role of human being that is coupled to the milieu and thenceforward generate the categorization schema.