I've always thought about it as the difference between "throwing something out of Earth's gravity" (launching a projectile with initial force only) versus "clim

I've always thought about it as the difference between "throwing something out of Earth's gravity" (launching a projectile with initial force only) versus "climbing [a ladder?] out of Earth's gravity" (continually applying force just over gravity's influence.) I think Bickerton has confused the two concepts. Consider that gravity is the weakest of all forces. You overcome it every time you jump, run (with both feet off the ground) or climb a ladder. You don't overcome it for long enough to get into orbit, but you still overcome gravity. Birds and airplanes regularly overcome gravity.