How did Galileo Galilei explain why people cannot feel Earth moving?

Galileo Galilei addressed the common objection that Earth’s motion should be perceptible by applying his early principle of inertia. He argued that because a body in motion tends to remain in motion, objects on the terrestrial surface—including projectiles and people—tend to share the Earth's motion.1

Consequently, this shared motion makes the Earth's movement imperceptible to those standing on its surface. By demonstrating that motion is relative and that objects naturally maintain their state of motion unless acted upon by an external force, Galileo provided a mechanical explanation that countered traditional Aristotelian objections to a moving Earth.1