Caption: "Drawing by Theodoros Pelecanos of Corfu (fl. later 15th century), in an alchemical tract entitled Synosius (1478)." (Slightly edited.)

Features:

1. A viscious circle: The snake or dragon eating its own tail is the Ouroboros (tail-devourer) which is an ancient symbol invented in ancient Egypt.

2. Yours truly CANNOT find the word Ouroboros (in ancient Greek Greek letters ουροβορος) in the image. But the author's handrwriting is NOT perfect.

3. In physics, there is often circularity too:
   A force law applied tells mass-energy how to move and then mass-energy tells how the force law is to be applied and then ...

4. However, in principle and hopefully in practice, a viscious circularity is avoided by finding a self-consistent solution. You need ingenuity.