“In order to judge of the form to be given to this institution [the Senate], it will be proper to take a view of the ends to be served by it. These were,—first, to protect the people against their rulers, secondly, to protect the people against the transient impressions into which they themselves might be led.”
James Madison in the Debates in the Constitutional Convention (June 26 1787), Journal of the Federal Convention, edited by E.H Scott(1893), pp. 241-42
From Wiki Quote (en.wikiquote.org)