If you want to hit a fade or a draw and you imagine throwing a pail of water and making the water go left or right, you wouldn't be far off.
If you want to have good tempo, and get the speed in the right place, just imagine throwing that pail of water and you'd be in business. If you swung back too fast, or tried to accelerate too soon with that pail of water, you'd either get wet, spill the water too soon, or both.
If you tried to throw that pail of water without making a good turn, or using your legs, you wouldn't make that water go very far. You'd have a hard time throwing that water just using your arms.
If you wanted to understand how the hands work together, again the pail of water image helps. Try to swing that pail with just the right hand moving towards the target, and the left side not pulling, and see where the water goes.
Throwing water from a pail can be very instructive. So can throwing anything heavy. Ben Hogan talked about thinking of throwing a medicine ball. It's the same idea. The acceleration is gradual, with real effort happening at the bottom.
I think I might try selling the idea--selling pails as a golf aid. You could have people on the range practising throwing the water. But then you'd have to have a tap, or a hose at the practice tee. And it isn't good to waste water. I guess the medicine ball is a better idea. But then you'd get tired pretty quickly: throwing a medicine ball. And you'd keep having to go and fetch it.
Okay, maybe it wouldn't work as a golfing aid. But I think it's a really good image. If you want a good swing, think about tossing that pail of water-- or the medicine ball. To each their own.