Although Cicero's family did not belong to the Roman aristocracy, he was supported in the competition for the consulship in 64 BC by most of Rome's rich and powerful (who called themselves the Optimati or "best people"), because they distrusted his aristocratic but less respectable rival, Catiline. The Optimati disliked and certainly looked down on Cicero, but they clearly considered him to be the lesser of two evils. Cicero won the election, whereupon Catiline organized a plot to overthrow the government. Cicero Tricked Catiline into revealing his plot and then ruthlessly suppressed the conspiracy. Several members of Catiline's group, including some aristocrats, were executed on Cicero's orders. Julius Caesar and some other Roman senators argued that Cicero had acted too hastily: he certainly had not given the conspirators due process of law. Because he could not refute the charges raised in the Senate, he left Rome in 58 BC. While he was abroad, he was formally proscribed and exiled. ("Proscription" was a process in which a criminal's name was posted on public billboards. Anyone was allowed to kill a proscribed person if he showed up in the city where the proscription was posted. It was, of course, the perfect way to enforce official exile.) After a year in Macedonia Cicero was exonerated and recalled to Rome at the instigation of Pompey. He occupied himself with reading and writing philosophy and stayed out of politics until 51 BC, when he accepted a one year posting as proconsul (governor) of the Roman province of Cilicia. (The normal tour for governors was only one year, to limit the possibility of corruption.)
Cicero returned to Rome in 50 BC, and at this point he finally had to take sides in the roiling political struggles that had racked Rome for the previous thirty years. He had to choose between Julius Caesar's faction and that of Pompey, who finally had revealed himself as Caesar's most bitter foe. Cicero chose Pompey, and Pompey, of course, lost the power struggle in 48 BC. But Cicero landed on his feet. Caesar's "unification policy" -- co-opting powerful former enemies -- saved Cicero and many others who had fought on the side of Pompey (including Casius and Brutus who eventually killed Caesar.) Cicero accepted Caesar's overtures of political friendship, and, while Caesar was virtual dictator of Rome, Cicero lived as a private citizen and devoted himself to his writings.
After Caesar's assassination in 44 BC, Cicero again returned to politics. Hoping to see a restoration of the Republic, he supported Caesar's adopted son, Octavian (later called Augustus) in the initial stages of Octavian's power struggle with Marc Antony. But in this case, Cicero had chosen sides too soon: Octavian and Antony were temporarily reconciled, and Cicero was proscribed and murdered on December 7, 43 BC.
Cicero made his reputation as an orator first in the law courts, where he preferred appearing for the defense and generally spoke last because of his emotive powers. Unfortunately, not all his cases were as morally sound as his justifiably famous attack on a particularly corrupt and inept governor of Sicily (Gaius Verres). The most famous of Cicero's political orations are the four speeches against Catiline and the fourteen so-called Philippics against Antony. Many of his court defenses and prosecutions are also preserved -- Cicero's friend, Atticus, served as his publisher.
In his writings, Cicero created a rich prose style that has exercised a pervasive influence on all the literary languages of Europe. His writing covers numerous subjects of intellectual interest, and he greatly enriched the vocabulary of his own language as well as those of the modern European tongues. Nearly all of his philosophical works were borrowed from Greek sources and, apart from their intrinsic merit, are of great value in preserving much of Greek philosophy that might otherwise have remained unknown. His treatises On the Republic, On the Laws, On Duty, and On the Nature of the Gods are particularly noteworthy, and they are still used in many universities. His rhetorical works, written in dialogue form, are of value as the products of an accomplished rhetorician and as a rich source of historical material. Among the minor works of Cicero, the treatises On Old Age and On Friendship have always been admired for their tone of cultivated geniality.
Highly important for historians are the almost 900 surviving letters written by Cicero to acquaintances and friends, more than half of them written to his friend and publisher, Atticus. The letters, unlike Cicero's public writings and utterances, are thought to reveal what Cicero really felt about his life and times and particularly about other Roman politicians. Even though they are often self-serving, and although many more letters are obviously missing (having been destroyed by Cicero's enemies after his death) they are revered as one of the most important primary sources of information on the politics of the final years of the Roman Republic.
Cicero's painstakingly prepared works were recognized, even by his contemporary enemies, as fine examples which should be preserved as exemplars for succeeding generations of orators and writers. That, taken with the fact that Cicero ensured that his best works were published and widely distributed by his friend Atticus, accounts for the fact that more of his work than anyone else's was preserved. Two thousand years later, Cicero is all over the Internet.
A sample of Cicero's orations and writings are available (in English and Latin) at The Perseus Project's Primary Latin Text Index: http://www.perseus.tufts.edu/Texts/latin_TOC.html#Cicero.
More is at http://www.fordham.edu/halsall/ancient/asbook3.html but you have to search the page.
Encyclopedia Britannica offers a good modern summary of Cicero's life and accomplishments (although it glosses over many of his faults): http://www.britannica.com/bcom/eb/article/4/0,5716,84794+1+82616,00.html.
Plutarch's biography, written in 75 AD, only 118 years after Cicero's demise, is more richly detailed but also less rigorous in separating known fact from conjecture: http://classics.mit.edu/Plutarch/cicero.html. Plutarch's description of Cicero's murder and the aftermath are at http://library.thinkquest.org/11402/moord_cicero_plu.html.
About.com has a page of Cicero Internet links: http://ancienthistory.about.com/homework/ancienthistory/msub_cicero.htm
The Loeb Classics hard copy editions of Cicero's works (more than 30 volumes, each, with Latin and English texts -- $20 each) are available for purchase at http://shop.barnesandnoble.com/booksearch/results.asp?WRD=Loeb+cicero&userid=4G5DTASKMV
P.S.: To best grasp the character
of Cicero, you should read the Sub Rosa series of mystery novels
written by Steven Saylor. They are a fun and painless way to learn a lot
about the end of the Roman Republican period. The Saylor Internet site
is at: http://www.stevensaylor.com/.
Scroll down past the ad for the Texas book (a good book, but not on our
subject.) Saylor's books are available through this page or from Internet