The vase of Gudea — two serpents, c. 2100 BCE

A green steatite libation vase of c. 2100 BCE, dedicated by Gudea of Lagash (ruled c. 2144–2124 BCE) to the god Ningishzida, a serpent deity attendant on Enki. Carved on it: two serpents coiled around a central staff, crossing each other at intervals, flanked by winged guardians. It sits in the Louvre. Enki himself is shown elsewhere with two streams pouring from his shoulders.

The motif is ancient, dated and undisputed. What it looks like is not a matter for anyone's permission: two strands winding about one axis and crossing at regular intervals is a topology, and you can check it with your eyes. This app's discipline is to show it at full strength and put a date-line under everything on the shelf — because the only thing here that is modern is the comparison, not the image. Then it stops talking. Every arrangement is an argument; you are allowed to make yours. The same double-serpent shape reappears in the Greek caduceus and, on this app's Hindu door, as iḍā and piṅgalā crossing around suṣumnā.