The Posterior Analytics contains Aristotle's Philosophy of Science. In Book 2, Aristotle asks how the scientist discovers what sort of loss of light constitutes lunar eclipse. The scientist has to discover that the moon's darkening is due to the earth's shadow. Once that defining explanation is known the scientist possesses the full scientific concept of lunar eclipse and can use it to explain other necessary features of the phenomenon. The present commentary, arguably misascribed to Philoponus, offers some interpretations of Aristotle that are unfamiliar nowadays. For example, the...