Caption: A postcard of an ox cart in Mexico, 1910. Transport as Aristotle (384--322 BCE) understood it.

Aristotle (384--322 BCE) and almost everyone before circa 1600 believed that motion was fundamentally different from being at rest and that motion was always detectable.

Features:

1. Bumping along behind the oxen without suspension on dirt roads or roads of flagstones or the like, you know you are in motion.

   The large wheels on the ox cart in the image helped getting over obstacles like ruts in the road.

2. If you are horse riding, you know you are in motion.

3. If you are sailing, you know you are in motion.

4. Now, of course, people before circa 1600 knew some motions were smoother than others. But before Galileo (1564--1642), no one imagined going to the limit of completely smooth motion and realizing that being in a reference frame with completely smooth motion was just like being in a rest frame if the motion was unaccelerated relative to an inertial frame. Actually, Galileo did NOT have a clear idea of inertial frames, but he was heading toward that idea.

   It is easier for modern people to accept that unaccelerated motion and being at rest are fundamentally the same because of our usually smoothly moving trains, planes and automobiles.

5. So before circa 1600, it was hard for people to accept the idea of the Earth's rotation and the Earth's orbital motion. Of course, a few people did accept it (e.g., Nicolaus Copernicus (1473--1543) and other early Copernicans), but they could NOT fully explain it from physical law. No one could before the advent of Newtonian physics in the later 17th century.

6. Some ancient Greek astronomers thought the Earth's motion was possible: i.e., Hicetas (c.400--c.335 BCE), Heraclides Ponticus (c.390--c.310 BCE), Aristarchos of Samos (c.310--c.230 BCE), and Seleucus of Seleucia (fl. 150 BCE). But most ancient Greek astronomers thought like Aristotle (384--322 BCE) and Ptolemy (c.100--c.170 CE) that the idea was absurd.