The senators were patricians, and so members by birth, or men of lesser birth who had notable achievements. Under the early kings, the Senate numbered 100, but grew to 900, then Augustus reduced it to 600. Even so only about 100 to 200 members were active at any given time. From time to time there were other sources of power in Rome, such as assemblies, magistrates, dictators and emperors, but the Senate always played a part.