Translation: E.F. Watling, 1966
Edition: Penguin, 1966
Review number: 290
Seneca's play based on the Oedipus legend faces probably the most difficult competition of all his works. This is because it is based on one of the greatest masterpieces of the Greek tragic theatre, Sophocles' Oedipus the King, also one of the best known of all Western plays.
The temptation, then, is to compare the two plays in a way which continually disparages Seneca's work. This is perhaps a little unfair, because we don't know what Seneca's purpose was in writing his plays: it is conjectured that they were intended to be read aloud by a group of friends, not performed in any conventional sense. But this is inferred from the non-dramatic nature of the plays and is not known by direct testimony. (Of course, too, the idea of what is "dramatic" and what is not has changed drastically as twentieth century playwrights have challenged the boundaries of the form.)
If we accept that Seneca wrote for a group of his friends (and it is a hypothesis which seems reasonably convincing to me), then we need to look at his plays remembering how people tend to write to their friends. A letter to a friend is full of private jokes, obscure references to shared experiences, assumed knowledge about common friends and interests. To apply this to Seneca's writing style may explain some of the ways in which he adapted his Greek sources.
The most obvious difference between Seneca's Oedipus and Sophocles' Oedipus the King is that the prophet Tiresias (and his guide) have, in the former, a very long scene in which a sacrifice is made and the augury taken. The guide describes the behaviour of the animals as they are killed and the appearance of the corpses as they are dismembered (since Teresias was of course blind). This scene would be impossible to recreate convincingly on stage - killing animals each performance would probably be considered ethically unacceptable, and even if it happened, you cannot guarantee that they will match the descriptions of their behaviour and organs given in the text. The scene would also be unconvincing if the sacrifices are made to take place off stage.
This long scene drastically reduces the dramatic impact of Oedipus' discovery of his true identity, and his (and Jocasta's) horror when the realisation dawns that he has murdered his father and married his mother. This fact must have been clear to Seneca - it is certainly blindingly obvious to any reader of the play. It seems to me that the reason he made this seemingly inexplicable change must be connected to the group of friends for whom the play was originally written. I don't know how accurate Tiresias' words are as a portrayal of the actual way in which seers read the omens. Whether it is or not, it sounds a bit like parody, containing lots of pompous mystical mumbo-jumbo. (Of course, any record of a fortune teller's words would sound like that to someone not convinced of their reliability - read any newspaper horoscope column with a cynical eye to be convinced of this.) If the person reading the part were either a well-known cynic, or a priest themselves, then we would have an excellent example of a private joke. In addition, this kind of joke provides a plausible reason why Seneca might be willing to reduce the dramatic impact of the play.
All this is conjecture; we can know very little about how Seneca thought as he wrote Oedipus. However it does provide an explanation of sorts as to why the play is so fatally flawed as a piece of drama.