Five of the brightest stars didn’t remain fixed in relation to other stars. They moved across the otherwise fixed star field. The motion of these wanderers, or planets, became the single most important phenomenon of science for millennia.

They not only moved across the fixed star field, but they would stop their motion, go backwards for awhile, and then move on ahead. Retrograde Motion – THE challenge of SCIENCE – and the stimulus giving birth to Sci/Tech.