Primary Source for composition of Senate?

[Frogumvir]

I am interested in finding out what primary sources are recommended on the subject of the senatorial order throughout the centuries of the Republic. Also, what do you think was the key to it becoming perhaps the most important element of the Roman government? It seems that the fact that it was comprised of magistrates and ex-magistrates, as well as the fact that Roman culture was hierarcichal and tradition based aided the senate massively. It senatus consultum were treated in a manner similar to laws.

[Emperor Goblinus]

Livy tells a great detail about the Senate, although I can't say offhand if he gave the actual size of the Senate as the centuries progressed.

[Primus Pilus]

Also, what do you think was the key to it becoming perhaps the most important element of the Roman government? It seems that the fact that it was comprised of magistrates and ex-magistrates, as well as the fact that Roman culture was hierarcichal and tradition based aided the senate massively.

 

The key to the senate's importance was that it initially was made up of the aristocracy of the Roman world. Whether or not we can be certain that the fall of the kingdom and the evolution into Republic happened the way we currently understand it or not doesn't even come into play. Regardless of the circumstances, the Senate was the one consistency in government from the city's earliest days... a place where the richest and most powerful met to deliberate and debate on governing issues. It's not that is was made up entirely of magistrates and ex-magistrates, but that it provided the pool of people for those all-important governing roles.

 

Some sources on the Senate can be found here:

http://www.unrv.com/forum/index.php?showtopic=8719

 

In particular try Dionysus, Livy and perhaps Cassius Dio as starting points.

[M. Porcius Cato]

Primary sources aren't the best place to begin for this topic because they're too fragmentary and indirect. Lintott's Constitution of the Roman Republic is a better starting point, and he provides copious references to the primary material.