Very similar and perhaps copied from this very treatise of Grosseteste on the rainbow—or from its source (Al-Hazen)—are some verses in the continuation of the French Romance of the Rose written by Jean de Meun, probably about 1270. Besides remarking of rainbows that—the words are Ellis’ translation—[1442]
“Only he who’s learned the rule
Of optics in some famous school
Can to his fellow men explain
How ’tis that from the sun they gain
Their glorious hues;”
the poet mentions burning-glasses and various types of mirrors, and also tells us that from optics one
“... may learn the cause
Why mirrors, through some subtle laws
Have power to objects seen therein—