I don't think Stoppardian has a precise definition.

The ordinary-sized stuff which is our lives, the things people write poetry about—clouds—daffodils—waterfalls—what happens in a cup of coffee when the cream goes in—these things are full of mystery, as mysterious to us as the heavens were to the Greeks.

It's where we're nearest to our humanness. Useless knowledge for its own sake. Useful knowledge is good, too, but it's for the faint-hearted, an elaboration of the real thing, which is only to shine some light, it doesn't matter where on what, it's the light itself, against the darkness, it's what's left of God's purpose when you take away God.

I write plays because dialogue is the most respectable way of contradicting myself.

A healthy attitude is contagious but don't wait to catch it from others. Be a carrier.

A scholar's business is to add to what is known. That is all. But it is capable of giving the very greatest satisfaction, because knowledge is good. It does not have to look good or even sound good or even do good. It is good just by being knowledge. And the only thing that makes it knowledge is that it is true. You can't have too much of it and there is no little too little to be worth having. There is truth and falsehood in a comma.

Poetical feelings are a peril to scholarship. There are always poetical people ready to protest that a corrupt line is exquisite. Exquisite to whom? The Romans were foreigners writing for foreigners two millenniums ago; and for people whose gods we find quaint, whose savagery we abominate, whose private habits we don't like to talk about, but whose idea of what is exquisite is, we flatter ourselves, mysteriously identical to ours.