From 1897 to 1922 he was professor of aesthetics and stylistics at the But Pirandello's greatest achievement is in his plays.
He wrote a large number of dramas which were published, between 19, under the collective title of Maschere nude [Naked Masks]. Pirandello is always preoccupied with the problem of identity.
The self exists to him only in relation to others; it consists of changing facets that hide an inscrutable abyss.
In a play like Cosí é (se vi pare) (1918) [Right You Are (If You Think You Are)], two people hold contradictory notions about the identity of a third person.
As characters they are part of the illusion of reality.
They reject the thought that they are literature, asserting that "This is life, this is passion." The play is a Meta theatre, which is a dramatic experimentation.
Six Characters in Search of an Author is about the relationship between art and life.
Especially it focuses upon the relationship between drama and the life. In the middle of the play rehearsal, several characters appear and request that an author be present to put them into the play.
The analysis and dissolution of a unified self are carried to an extreme in Sei personaggi in cerca d'autore (1921) [Six Characters in Search of An Author] where the stage itself, the symbol of appearance versus reality, becomes the setting of the play.
The attitudes expressed in L' Umorismo [Humour], an early essay (1908), are fundamental to all of Pirandello's plays.