The Satyricon is a novel by Gaius Petronius Arbiter (usually just known as Petronius), who lived in the first century CE and was an adviser to Emperor Nero. It has sometimes been described as "the first novel." Our view of it today is often shaped by what we already know (or have been told) of its historical context and by the semi-mythical picture of "ancient Rome" that is a part of the collective consciousness of our time (and earlier).

Much of the novel contains quite graphic sexual scenes and has a general air of corruption and debauchery. Though it may not be obvious to the reader at first, it becomes more evident as one progresses through the novel that many of the goings-on are probably being depicted satirically. In my opinion, the key to Petronius's main theme can be found in the opening chapters, in which he criticizes the educational system of his time:

It is my conviction that the schools are responsible for the gross foolishness of our young men, because, in them, they see or hear nothing at all of the affairs of every-day life, but only pirates standing in chains upon the shore, tyrants scribbling edicts in which sons are ordered to behead their own fathers; responses from oracles, delivered in time of pestilence, ordering the immolation of three or more virgins; every word a honeyed drop, every period sprinkled with poppy-seed and sesame. [trans. W.C. Firebaugh]

This presumably becomes the author's rationale for describing in detail in his book just such "affairs of every-day life" not covered in school.

The novel is basically a series of almost dreamlike episodes involving sex, orgies, excessive eating and drinking, criminal behavior, and general foolishness, interspersed with observations about society, literature, art, and other topics. It's open to debate how much of this is a criticism of behavior which even for its time and place was probably considered excessive, how much is merely description without any implied judgement, and how much represents the author's own reveling in or endorsement of such thinking and such activities. You might wish to consult literature from Petronius's approximate era, or that immediately following it, such as Tacitus's The Annals of Imperial Rome, to get some idea of the actual ethics of ancient Roman society. It would also be good to compare Petronius's type of satire with that of other important writers of the approximate period or slightly earlier, such as Horace and Juvenal. What is it, one might ask, that makes Petronius different from more "respectable" writers, apart from the sex and general debauchery shown in the Satyricon?

Petronius was known as the arbiter elegantiarum (arbiter of elegance or taste) at Nero's court. In historical fiction such as Henryk Sienkiewicz's famous novel Quo Vadis, Petronius is depicted as something of a hero in spite of his own narcissism and hedonistic lifestyle, a man attempting to curb Nero's excesses and eventually having the integrity to stand up to him and to others in his administration who are leading Rome on a downward path. While this is a romanticized view, the historical Petronius did eventually run afoul of Nero and, like others in his predicament (such as Seneca), committed suicide rather than face imprisonment or execution. One might ask to what degree the Satyricon reveals this non-conformist, rebel side of its author, or whether the novel is simply an expression of the amorality and corruption of Petronius's time.