It’s to do with knowing and being known....

It’s to do with knowing and being known. I remember how it stopped seeming odd that in biblical Greek, knowing was used for making love. Whosit knew so-and-so. Carnal knowledge.
[...]
Having that is being rich, you can be generous about what’s shared – she walks, she talks, she laughs, she lends a sympathetic ear, she kicks off her shoes and dances on the tables, she’s everybody’s and it don’t mean a thing, let them eat cake; knowledge is something else, the undealt card, and while it’s held it makes you free-and-easy and nice to know, and when it’s gone everything is pain.

For full extended monologue, please refer to clips or the script edition cited here: Stoppard, Tom. The Real Thing. Faber and Faber, 1982, pp. 62-3.