The history of “laudable pus” is messier and more revealing than the popular version. Ancient physicians did distinguish between kinds of wound discharge. Hippocratic writings treated thick, non-offensive pus as a better sign than thin, foul discharge. Galen is often blamed for turning pus into a requirement for healing, but modern historical reviews argue that this is too simple: Galen also recommended treatments intended to dry wounds and reduce suppuration.
By the medieval period, however, the idea that a healthy wound should pass through a productive suppurative stage had become deeply entrenched in surgical practice. Importantly, it was never uncontested. Theodoric Borgognoni argued in the 13th century that wounds did not need to form pus, and Henri de Mondeville made similar objections in the early 14th century. Their opposition is one reason this card uses a medieval representative start rather than pretending that one exact doctrine ran unchanged from Hippocrates onward.
Why did the idea persist? Before microbes, antisepsis, or antibiotics, infection was extremely common. Surgeons learned to distinguish relatively localized, thick white pus from foul, spreading, often lethal infection. A patient producing the former could genuinely fare better than one producing the latter, making suppuration look like part of successful healing.
Semmelweis, Pasteur, Lister, germ theory, and antiseptic surgery changed the causal interpretation. The goal became preventing contamination and infection rather than encouraging a supposedly necessary stage of pus formation.