Gunner firing a cannon, 16th-century illustration. The path of the projectile is shown according to Aristotelian physics. Since Aristotle believed that no body could undertake more than one motion at a time, the path had to consist of two separate motions in a straight line. The actual trajectory is a parabola. Artwork from 'Problematum astronomicorum et geometricorum' (Basel, 1561) by Dutch mathematician and astronomer Daniel Santbech.