Abstract: In 1761, John Tuberville Needham published a study arguing that the hieroglyphic inscriptions of an Isis statue held in Turin could be read through the knowledge of Chinese. The study provoked a vigorous and acrimonious debate in the scholarly word of the time. Not only would Needham’s decipherment give access to the coveted records of Egypt, which had resisted all previous attempts at cracking their code, but it would demonstrate once and for all that the customs of China could be read through the antiquity of Egypt, and that the comparison of the two was the key to harmonizing the historical record of the Far East with the Bible. Vertiginous scientific and theological consequences were at stake. The Isis of Turin affair revolved entirely around issues of cultural comparison: what to compare? How? And why? A precious collection of disagreements about the practice of cultural comparison at the crucial turn of the 18th century can be found clustered around this case. The intellectual infrastructure that made this comparative debate resonate as it did in its time belongs to a distinctive epistemological moment. In time, what had been hailed as a cornerstone of world history had become a fading foil. Before it was completely forgotten, the Isis of Turin affair came to stand for the error of a previous time’s knowledge in a period that conceived itself going through rapid scientific progress. Within the space of a few years, the whole edifice of knowledge that had allowed it to emerge was no longer in place.