This volume, rich in illustrations (reproductions, photographs and surveys) offers, by means of the study of two monuments by Brunelleschi, an impassioned and thoroughly argued discussion of proportion in architecture. This work earned the author the 2012 award of the James Ackerman Prize for History of Architecture, and thus it was published by the CISA in Vicenza.

Matthew Cohen presents his point of view on the topic of proportion in architecture, contrasting it with what he refers to as the “Wittkower paradigm” (p. 36 ff), the axiom connected to the set of numerical and geometrical characteristics that were treated by the authoritative historian around middle of the twentieth century. That treatment, received very favourably by critics and collecting illustrious followers, was set out in Architectural Principals in the Age of Humanism.

Cohen’s deductions emerge in relation to the relationships between the church as designed by Brunelleschi, the earlier late-Medieval design, and later interventions that over time have resulted in the actual design of San Lorenzo, by means of both accurate metrical surveys documented in the volume and a detailed discussion of the various historiographical hypotheses proposed up to the most recent times. The complex relationships between the medieval design and that of the Renaissance is very carefully investigated.

A particular asset of the work is the knowledge it demonstrates of late medieval mathematics, of which various unpublished aspects are set forth. The particular measurements in braccia of the intercolumniation in San Lorenzo shows the familiarity of Humanistic culture with those aspects. In 503 A.D., Severino Boethius (475–525 A.D.), the author of treatises on the quadrivium (the structure that had given for a millennium to scientific knowledge, constituted of arithmetic, music, geometry and astronomy), had proposed that the numerical series were the structures that render numbers most interesting. The numbers that descend from geometric figures are the foundations of his number theory, which contains three types of geometric numbers: linear (one-dimensional), polygonal (two-dimensional) and pyramidal (three-dimensional). The development of this theory gave rise to the construction of particular series. One of these is present in the bay of San Lorenzo as a matrix for the design. Cohen makes a significant contribution to knowledge that reveals the previously unknown meaning of the use of some numbers that recur in Brunelleschi’s architecture: the sequence 9, 13, 17, 21, of the series of the “gnomons of hexagonal pyramidal numbers” (p. 94).

In his final considerations, Cohen places the accent on the mental nature of proportional constructions, which he believes to be in contrast to Wittkower’s visual idea of it. This contrast, connected to the use of the term “aesthetic” in reference to proportion, perhaps descends from the different training and backgrounds of the two scholars: the humanistic scholar used the term in its original meaning of “relative to the knowledge filtered through the senses”, according to which the perception of beauty is a consequence of the harmony implicit in the creation, while the younger scholar, of a scientific formation, uses it in the more superficial sense in current use, relative to “beauty in art”.

In the last century, Wittkower, as a historian and without surveys, blazed a fascinating trail, which led numerous architects to undertake surveys and historic studies, inducing them to measure with ancient units of measure. In his commendable work Cohen covers a good bit of ground. I believe the initiator would have appreciated this work.

Translated from the Italian by Kim Williams.