How did Francesco Borromini’s approach to architectural proportion differ from Gian Lorenzo Bernini’s?

Francesco Borromini’s approach to architectural proportion differed fundamentally from that of Gian Lorenzo Bernini, primarily in their reliance on distinct theoretical foundations.12

While Bernini adhered to the traditional anthropometric basis of architecture—the belief that building proportions should be derived from the proportions of the human body, reflecting the idea that humans were created in the image of God—Borromini rejected this as his primary method. Instead, Borromini based his designs on complex geometric configurations and modules, a practice he likely adopted from medieval building procedures he learned in Lombardy.21

This divergence became a point of professional contention. Bernini, who favored the anthropometric tradition, accused Borromini of abandoning the fundamental basis of good architecture. Borromini, however, did not entirely divorce his work from human references; he occasionally noted that his designs contained such allusions, such as his interpretation of the facade of St. Philip Neri as a welcoming gesture of outstretched arms. Ultimately, Borromini’s reliance on geometric subunits allowed for the fluid, undulating, and intricate spaces that characterize his unique contribution to the Baroque style.23