Pendulum Swings On Potential

Pendulum swings high, swings low, swings high, up. A pendulum stopped, needs a push or pull like a child wiggling to go in playground. Push me, pull me, push me up, till I fly. Once started, gravity sustains the swing. going high, gravity tugs and pulls down. As it falls tethered on string, speed builds up carrying it down, then up high, until Gravity's elastic drag stops the up. The pendulum weight hangs floating and poised, before it free falls on string to swing down. The pace is fast at first, then slows right down. Potential gained by the elevation sustains the swing's perpetual motion. But friction's drag spoils the fun of swing, otherwise the pendulum would swing up down, up and down, up again forever.