Most slaves were barbarian captives, taken as a result of war and purchased by land and home owners at a 'vile price'. Due to their former freedom and independence they were anxious to break free of their masters and exact revenge for their current condition. Therefore, they had to be restricted lest their insurrections reduced the republic to the brink of destruction. At times in Rome there were a greater number of slave than free which did cause a fair amount of turmoil within the city.
A slaves condition within a Roman home was solely dependent upon the temper of the dominus - master. It was not uncommon for a dominus to carry out his wrath on the slave unto the point of near death or even death itself. This knowledge filtered up to the government who eventually ruled that they, not the home owner, had the responsibility for the life or death of the slave thus giving slaves more freedom.
Salves were forbidden to participate in government affairs for 3 to 4 generations from their capture but eventually they did move into the senate and other high positions of government.
Although they were forbidden to participate in government affairs, most notably the senate, they played important roles in the theater where they acted in ways which they would not be allowed to do in regular life. Since the southern part of Italy was heavily influenced by the customs of the Greeks, slaves were given more freedoms than that which was allowed by the Romans such as marrying, owning land, and borrowing money.
This, in a sense, opened the eyes of the Romans to customs of other lands thus enlightening their thinking. Even though they were barbaric they quickly adopted certain manners and customs of those whom they conquered thus making them wiser to the ways of the world.
The Greeks tried to unsuccessfully preserve the pure blood line of their culture while the Romans realized that to emulate this ideology would produce the downfall of the Roman Empire. Rome; therefore, instituted a policy whereby all natives of Italy were born Roman citizens. This allowed the entirety of Italy to unite under the Roman banner and into a nation based upon a common language, Latin, civil institutions and the weight of the Roman empire. There was a downside though, and that was mostly everyone became servants.
"Wheresoever the Roman conquers, he inhabits." wrote Seneca. Whether conquering was by compulsion or volition, as a Roman citizen you were forced to comply with the rules and laws of the government and at the same time, receiving her benefits.
One of the benefits, which the Roman government cherished and fostered to a great extent, was the Latin language. By the use of arms, Latin was spread to Africa, Spain, Great Britain and beyond. Along with the advent of the language came the 'dignity in letters', as evidenced by Lucan, Martial, Quintilian and others, all born on foreign soil. The Greeks thought better of themselves and were not inclined to adopt another language, especially one coming from the unpolished Romans. It was common, though, in Italy to find those in government, business and places of authority speaking both Latin and Greek.