An important ingredient of satire is irony. Irony refers to the production of double meanings via any one or more of several devices: contrast, contradiction, incongruity, etc. Irony is especially present in satire made up of indirect aggression. A well known ironic device used by literary satirists is the irony of allegory. An allegory is an entire story created and presented for the purpose of producing two different levels of meanings. One level is immediately perceivable and it is one that is not intended by the allegorist, and the other is hidden and which constitutes the real meaning that the allegorist wishes his/her audience to take away with them. ''Allegory presents its messages in terms of something else, a literal set of events, persons, conditions, or images having a corresponding level of existence involving meaning, conceptions, values, or qualities.'' (Test, 1991:187) The important point, however, is that in satiric allegories, the two different levels of meanings are set in opposition to each other producing thereby irony. A classic allegorical tale is George Orwell's Animal Farm, as is Jonathan Swift's Gulliver's Travels. The film Planet of the Apes is another example of allegory, but in cinematic form. In both these instances the story itself comprises an entirely imaginary or fictitious world, but possessing all the characteristic features of the human world, and it is presented in order to contrast with the real world for judgmental reasons. Such fictitious worlds created for this purpose have been variously labeled as utopias, dystopias, beast fables, and science fiction. Often writers will produce combinations of these different worlds rather than rely on one specific type. In allegorical satire, it may be noted, the irony is not only inherent in the creation of the parallel (but contrasting and oppositional) worlds of the real and imaginary, but the irony itself also serves to act as satire. George Orwell's Animal Farm is both ironical and satirical. (See also parody)