An example of a metaphor used in explaining science:
"Then Mercury runs on seven circles in all; Venus on five; the earth on three, and round it the moon on four; finally Mars, Jupiter, and Saturn on five each. Altogether, therefore, thirty-four circles suffice to explain the entire structure of the universe and the entire ballet of the planets."
Copernicus, N. (1959) The Commentariolus (first prepared in Latin in 1514, Translated by. E. Rosen), in Three Copernican Treatises (Ed. E. Rosen) Dover Publications.
The reference to circles links to the historical conceptions tat heavenly bodies only moved in perfect circles. This alternative conception was a major obstruction to the development of modern astronomy.
Read about the conception of heavenly circular motion
