Plot in Greek tragedy, the movement of the whole play, is discussed so extensively by Aristotle that little need be added. For his preoccupation with Sophocles hardly makes his exposition the less comprehensive. Later criticism has generally accepted Sophocles as historically midway between the occasional archaism of Æschylus and the occasional modernism of Euripides, as typical of Greek dramatic habits, and as the greatest Greek master of plot. Sophocles, as has been often pointed out, intensified drama by making his unit not the trilogy, but the single play, by developing a single theme with a clear conflict, and by making its interaction self-sufficient through the use of a third actor. Euripides, on the other hand, seems to care less for totality, though he achieves it in some plays, notably in the _Medea_. His use of a separable prologue instead of dramatic exposition within the play has been condemned as impatient;[12] and the vividness of his lines, especially in description, has been disparaged as distracting. In all this the art of Sophocles is no more eminent than it is typical. He is the shining example of Greek artistic economy. This characteristic economy of Greek tragic art makes it permanently inspiring to playwrights. Modern audiences, being less conscious of art, may find the economy sometimes too close; but playwrights discern in it both a triumph of technic and an example. For the revolt against even the “unities” of the French classic stage spent its force long ago. Meantime the war of the romanticists against the classicists should make clear, what the greatest dramatists have always understood, that unity in drama is valuable only as a means to coherence. Its only _raison d’être_ is to clear the way for steady movement and to lead that movement to a convincing issue. Now in this compelling force of movement Greek drama, especially in the hands of Sophocles, remains by common consent a model of tragic art. That even audiences habituated to variety and tolerant of looseness will still feel this force is suggested by revivals of increasing frequency, by the eminence, even in a period of very different dramatic habits, of such plays as _Othello_, and by the deliberate preference of some recent dramatists[13] for the Greek model. But whether single, steady movement through a limited time be a permanent dramatic principle or not, at least it is characteristically Greek. What one editor says of the _Antigone_ of Sophocles might be said of Greek tragedy generally: “there is no halting in the march of the drama.”[14]