Full Idea
When the nobility is numerous, there must be a senate to regulate those matters which the body of nobles is incapable of deciding. Thus aristocracy of a kind resides in the senate, democracy in the body of nobles, while the people is nothing.
Gist of Idea
If the nobility is numerous, the senate is the artistocracy, and the nobles are a democracy
Source
Baron de Montesquieu (The Spirit of the Laws (rev. 1757) [1748], 02.03)
Book Reference
Montesquieu,Baron de: 'Selected Political Writings', ed/tr. Richter,Melvin [Hackett 1990], p.119
A Reaction
This presumes that the body of nobles elects the senate.