Ibsen is no preacher, and he has told us expressly that _Ghosts_ 'preaches nothing at all.' This pursuit of truth to its most secret hiding-place is not a sermon against sin; it sets a scientific dogma visibly to work, and watches the effect of the hypothesis. As the dogma is terrible and plausible, and the logic of its working-out faultless, we get one of the deeper thrills that modern art has to give us. I would take _A Doll's House_, _Ghosts_, and _The Wild Duck_ as Ibsen's three central plays, the plays in which his method completely attained its end, in which his whole capacities are seen at their finest balance; and this work, this reality in which every word, meaningless in itself, is alive with suggestion, is the finest scientific work which has been done in literature. Into this period comes his one buoyant play, _An Enemy of the People_, his rebound against the traditional hypocrisy which had attacked _Ghosts_ for its telling of unseasonable truths; it is an allegory, in the form of journalism, or journalism in the form of allegory, and is the 'apology' of the man of science for his mission. Every play is a dissection, or a vivisection rather; for these people who suffer so helplessly, and are shown us so calmly in their agonies, are terribly alive. _A Doll's House_ is the first of Ibsen's plays in which the puppets have no visible wires. The playwright has perfected his art of illusion; beyond _A Doll's House_ and _Ghosts_ dramatic illusion has never gone. And the irony of the ideas that work these living puppets has now become their life-blood. It is the tragic irony of a playwright who is the greatest master of technique since Sophocles, but who is only the playwright in Sophocles, not the poet.