Imagine playing a game of billiards, putting a bit of counter-clockwise spin on the cue ball and watching it deflect to the right as it strikes its target ball. With luck, or skill, the target ball sinks into the corner pocket while the rightward-deflected cue ball narrowly misses a side-pocket scratch. Now imagine your counter-clockwise spinning cue ball striking a bowling ball instead, and deflecting even more strongly—but to the left—when it strikes the larger mass.