Aristotle‘s three unities are the principles of grammatical structure relating to action, time and place. The unity of action demands that the action of a tragedy must be a complete whole. In an action there may be several incidents and events but together, they must constitute one action. The unity of time means that the action of the play should take place in a short internal chronology, ideally no more than 24 hours and the unity of play stands that the action should take place in a minimal number of locations. These three unities, have since the Renaissance, been considered to be necessary to create credibility in a play. The more elaboration are discussed below-
Tragedy then is a representation of an action that is worth serious attention, complete in itself and of some amplitude.
It indicates that the action must be complicated.
Now a whole is that which has a beginning middle and an end.
Beginning must not necessarily follow out of some previous situation, there must be earlier part of the story. The beginning must be clear and intelligible. It is neither be too long nor too short in size. Then the middle which is consequent upon a situation that is connected with beginning. And finally, the end which is followed by nothing.
Unity of time is the second of three unities. Unity of time refers that the action of a play should occur within a single circuit of the sun. The action does not continue more than 24 hours. Aristotle says,
According to Aristotle, the spectators will not believe the reality of an action if a drama lasts more than a single day. If the spectators remain disbelieve the action of a tragedy, it will fail to arouse fear and it will be a futile one.
The unity of place means that the action of a drama must take in a single place. Aristotle puts his favour on unity of place by saying that,
In a play one cannot represent an action with a number of parts going on simultaneously; one is limited to the part on the stage and connected with actors.
From the above discussion, it is clear to us that these three unities are essential part of a successful tragedy. Aristotle mentioned their formative unities by considering at the time of his own. But he lays emphasize on unity of action and says it as the controlling law of a drama.