A Pirandello Play

In a famous Pirandello play (“Six Characters in Search of an Author”), there is a dialogue between a character (fully conscious of its condition as “character”) and the producer (who performs the role of a man in flesh and blood) during which the former expresses its doubts about the so called self-identity of the latter.
Here is the relevant part of that dialogue:

“FATHER (the character): … and once again I ask you in all seriousness; ’Who are you?’
PRODUCER (turning to the Actors in utter amazement, an amazement not unmixed with irritation):
What a cheek the fellow has! A man who calls himself a character comes here and asks me who I am!
FATHER (with dignity, but in no way haughtily): A character, sir, may always ask a man who he is. Because a character has a life which is truly his, marked with his own special characteristics. And as a result he is always somebody! Whilst a man … And I’m not speaking of you personally at the moment … Man in general … can quite well be nobody.
PRODUCER: That may be as it may? But you’re asking me these questions. Me, do you understand? The Producer! The Boss!
FATHER (softly, with gentle humility): But only in order to know if you, you as you really are now, are seeing yourself as, for instance, after all the time that has gone by, you see yourself as you were at some point in the past… With all the illusions that you had then … with everything … all the things you had deep down inside you … everything that made up your external world … everything as it appeared to you then … and as it was, as it was in reality for you then! Well … thinking back on those illusions which you no longer have … on all those things that no longer seem to be what they were once upon a time … don’t you feel that … I won’t say these boards … No! … that the very earth itself is slipping away from under your feet, when you reflect that in the same way this you that you now feel yourself to be … , all your reality as it is today … is destined to seem an illusion tomorrow?
PRODUCER (not having understood much of all this, and somewhat taken aback by this specious argument): Well? And where does all this get us, anyway?
FATHER: Nowhere. I only wanted to make you see that if we (again, pointing to himself and to the other Characters) have no reality outside the world of illusion, it would be as well if you mistrusted your own reality The reality that you breathe and touch today … Because like the reality of yesterday, it is fated to reveal itself as a mere illusion tomorrow.