So, is kneading a throw-back to nursing behavior? Is that why cats get hypnotic while the do it?

I think I've heard that, MonkeyButter. I think the kneading and the purring are what convinces the mama to let the milk to flow?

very interesting . . .

Yes, it's kitten behaviour. You can see here the kittens here kneading the mother to stimulate the flow of milk. Often the cat drools, and this, too is to stimulate milk flow.

Domestic cats will carry on this behaviour into adult life, directed at the person or animal they see as a parent figure.

Interestingly, although my cats are mother and daughter, Lucy, the daughter, sees me as her parent figure and will knead when she jumps up next to me on the sofa or bed, or, if she falls on her back for me to rub her tummy, her front paws will 'knead' in mid-air.

But when she and Bailey curl up on their beanbag, Lucy will often lie in a 'kitten position' with her head against her mother's tummy.

"You're carrying a lot of tension in your scruff..."