- For the concept of protasis in linguistics, see Conditional sentence.
In
drama, a
protasis is the introductory part of a play, usually its first act. The term was coined by the fourth-century
Roman grammarian
Aelius Donatus. He defined a play as being made up of three separate parts, the other two being
epitasis and
catastrophe. In modern dramatic theory the term
dramatic arc has substantially the same meaning, though with slightly different divisions.