<P> Tragedy and comedy were viewed as completely separate genres, and no plays ever merged aspects of the two . Satyr plays dealt with the mythological subject matter of the tragedies, but in a purely comedic manner . </P> <P> The power of Athens declined following its defeat in the Peloponnesian War against the Spartans . From that time on, the theatre started performing old tragedies again . Although its theatrical traditions seem to have lost their vitality, Greek theatre continued into the Hellenistic period (the period following Alexander the Great's conquests in the fourth century BCE). However, the primary Hellenistic theatrical form was not tragedy but' New Comedy', comic episodes about the lives of ordinary citizens . The only extant playwright from the period is Menander . One of New Comedy's most important contributions was its influence on Roman comedy, an influence that can be seen in the surviving works of Plautus and Terence . </P> <P> The plays had a chorus from 12 to 15 people, who performed the plays in verse accompanied by music, beginning in the morning and lasting until the evening . The performance space was a simple circular space, the orchestra, where the chorus danced and sang . The orchestra, which had an average diameter of 78 feet, was situated on a flattened terrace at the foot of a hill, the slope of which produced a natural theatron, literally "seeing place". Later, the term "theatre" came to be applied to the whole area of theatron, orchestra, and skené . The coryphaeus was the head chorus member who could enter the story as a character able to interact with the characters of a play . </P> <P> The theatres were originally built on a very large scale to accommodate the large number of people on stage, as well as the large number of people in the audience, up to fourteen thousand . Mathematics played a large role in the construction of these theatres, as their designers had to be able to create acoustics in them such that the actors' voices could be heard throughout the theatre, including the very top row of seats . The Greek's understanding of acoustics compares very favourably with the current state of the art . The first seats in Greek theatres (other than just sitting on the ground) were wooden, but around 499 BCE the practice of inlaying stone blocks into the side of the hill to create permanent, stable seating became more common . They were called the "prohedria" and reserved for priests and a few most respected citizens . </P>

What type of space was used during the greek theatre era