The main use of catharsis in literary contexts derives from a phrase in Aristotle’s Poetics that refers to the catharsis of the “pathemata”. The precise meaning of the term has been widely debated in the scholarly community for several centuries, because it is not clearly explained by Aristotle.
A common Greek usage of the term means “purification” in a medical sense of purgative. The pathemata are sufferings, in the sense of emotional reactions (the Greek has a sense of the passive, i.e. of things suffered). In some way tragedy serves to purify these by means of fear and pity.
Whether this means to make the emotions better regulated, more appropriate, or to “vent” them and get rid of them is not absolutely clear from the syntax of the Greek phrase.
Actually catharsis never means revelation and has never meant it. It means purification. Purifying yourself of prior misconceptions may *result* in new ideas/revelationss\, but that is not the same as catharsis meaning revelation.
"Catharsis", used in modern day language usually refers to a revelation of some type, it is when a state has been changed, usually for the better since it has a positive connotation. The word is also used when a 'growth' has occurred. One can have a "cathartic intervention" implying that you are now able to perceive a situation in a "new light" to your advantage, thus allowing you to free yourself of a preconceived "bias" or notion and permitting a channel to flow in a new direction. It is similar to an 'epiphany' in that you are able to view a concern or matter in an entirely different way, although 'catharsis' somehow implies a natural procedure relating to a "time process" whereas the epiphany implies a more immediate "aha" effect.