Ptolemaeus

A Latin inscription next to him reads “In this mountain range, King Ptolemaeus uses a world-compass and through astrology, by longitudes and by latitudes, he constructed a mappa mundi and a cosmography.”

This was unfortunate not only because Ptolemaeus’s system was wrong, but because it seemed to endorse a measurement of the earth’s circumference of 18,000 miles—a significant underestimate.

Ptolemaeus’s epochal influence has had the effect of making ancient astronomy seem, to us, a lot less diverse than it was.

Modern popular astrology runs directly back to Claudius Ptolemaeus, whom we call Ptolemy, although he was unrelated to the kings of the same name.

It will be noted that Irenaeus, in his controversy with Ptolemaeus, makes no mention of the fourth Gospel, but falls back on a tradition.