A physician’s attack on the idea that the proportions of the orders are fixed by nature. Perrault showed that ancient buildings disagree, argued that beauty is partly custom, and proposed simplified proportions obtained by averaging.
Perrault, translator of Vitruvius and designer of the east front of the Louvre, distinguished positive beauty (founded on convincing reasons such as rich materials, size and precise workmanship) from arbitrary beauty, which pleases only through habit and authority. The exact proportions of the orders, he argued, belong to the second kind.
His practical proposal was to adopt a new, easily remembered module (a third of the diameter) and proportions midway between the extremes of the ancient examples. The argument that architectural rules are conventions, not laws of nature, reverberated through the eighteenth century.
The book, part by part
I The argument
Positive and arbitrary beauty; the averaged proportions of the five orders, rising in equal steps of two modules.