Readings on: The roles of observation and mathematics

Tycho Brahe –

Danielson, Dennis R., Ed; The Book of the Cosmos [abridged– 550 words] — the heavens are not eternal. Changes take place.

Johannes Kepler –

Randall, John R. The Making of the Modern Mind [abridged– 620 words] — the heavens follow regular mathematical laws not different from the earth's