It's The Law
The kneeling slave remains dutifully focussed on his mistress’s shoe and sock on her rightfoot which is resting stationary on the ground, even though her left foot is dangling and swivelling subliminally in the air, causing lots of exciting creases and folds in the sock, whilst she is lost in her happy telephone conversation with her boyfriend. That’s because, by law, the slave must focus on whichever shoe and sock is closest to him.