Mathematicians Of The Day

15th November

Quotation of the day

From Johannes Kepler
On how the motion of a planet defines its sphere:
... and thus it comes about gradually by the linking and accumulation of a great many revolutions that a kind of concave sphere is displayed, having the same center as the Sun, just as by a great many circles of silken thread, linked with each other and wound together, the dwelling of a silkworm is made.
Harmonice mundi (Linz, 1619) Book 5, Chapter 9, 4. Axiom, trans. Aiton, Duncan and Field, p. 453.