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μίμησις ούκ άνθρώπών άλλά πραξεως καί βίον (from Poetica, Aristotle): *
The full quote from the Poetic (lines 15 thru 19):
Character gives us qualities, but it is in our actions— what we do—that we are happy or the reverse. In a play accordingly they do not act in order to portray the Characters; they include the Characters for the sake of the action. So that it is the action in it, i.e. its Fable or Plot, that is the end and purpose of the tragedy; and the end is everywhere the chief thing. Besides this, a tragedy is impossible without action, but there may be one without Character.
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surface in Euclidean geometry:*
geometry named after Euclid, Greek mathematician who lived circa 300 BC. His “The Elements” is a collection of axioms, theorems & proofs about squares, circles acute angles, isosceles triangles. It is 1 type of geometry, the other geometers belong to non-Euclidean and include spherical & hyperbolic- see below:

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Riemann (theory of algebraic equations): *

ABIVE Illustration of a Riemann surface for the function f(z) = √z. The 2 horizontal axes represent the real and imaginary parts of z, while the vertical axis represents the real part of √z. The imaginary part of √z is represented by the coloration of the points.
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Classical drama (the mask): *
The mask transformed the actor as much as memorization of the text; performance did not distinguish the masked actor from the theatrical character. The mouth opening was relatively small, preventing the mouth being seen during performances; this small size argues against the mask as a megaphone. In a large open-air theatre (the Theatre of Dionysus, Athens) they created a sense of dread, even large scale panic since they had intensely exaggerated facial features & expressions. The actor could appear & reappear in several different roles preventing the audience from linking the actor to a given character. Only 2-3 actors were allowed on the stage & masks permitted quick transitions from one character to another. There were only male actors, but masks allowed them to play female characters. Their variations distinguished sex, age & social status & might reveal change in a particular character's appearance ( e.g. Oedipus after blinding himself). Masks were also created for specific characters and events in a play (eg The Furies in Aeschylus' Eumenides). Masks were also worn by the chorus. All 12 to 15 members of the tragic chorus wear the same mask as they represent 1 character. This created a sense of unity while representing a multi-voiced persona or single organism & encouraged interdependency & a heightened sensitivity between each individual of the group.
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Greek theatre (size): *
the Theatre of Dionysus was built mid 6th century BC to host the City Dionysia, reaching its full extent 4th century BC when it had a 17,000 capacity. The works of Aeschylus, Sophocles, Aristophanes and Euripides were all performed here.
