There's no doubt about it. Arcadia is Tom Stoppard's richest, most ravishing comedy to date, a play of wit, intellect, language, brio and, new for him, emotion. It's like a dream of levitation: you're instantaneously aloft, soaring, banking, doing loop-the-loops and then, when you think you're about to plummet to earth, swooping to a gentle touchdown of not easily described sweetness and sorrow.
Even one word, or certainly one sentence, should be able to describe the basic characteristic that the scene has, or the character has, or the story has. And then you begin to detail that one spine, and you have offshoots from that spine, and it becomes more and more complex, but all of it stems from that one-word, one-line theme, which can give the character, the scene, or the play its uniqueness.