A kiss is just a kiss

. . . except when it isn't. Jack Burden learns the laws of love, gravity, and path dependence in chapter 7 of Robert Penn Warren, All the King's Men (1946):

Jack Burden kisses Anne Stanton

"Aren't you happy?" she asked, leaning.

"Sure," I said, and was as happy, I suppose, as I deserved to be. But the thing was there all the time, breathing back there in the dark of my mind and waiting to pounce. Even though I forgot it was there. Then, the next night when she didn't kiss me in the new way, I felt the thing stir. And the next night. Because she didn't kiss that new way I was even angrier than I had been when she had. So I kissed her the way that man in Maine had done. She drew back from me immediately and said, quite quietly, "I know why you did that."

"You liked it well enough up in Maine," I said.

"Oh, Jackie," she said, "there isn't any place called Maine and never was, there just isn't anything but you and you are all forty-eight states together and I loved you all the time. Now will you be good? And kiss me our way?"

So I did that, but the world is a great snowball rolling downhill and it never rolls uphill to unwind itself back to nothing at all and nonhappening.