The purpose of the Constitution is to restrict the majority's ability to harm a minority.
James Madison[Regarding legislative assemblies,] the number ought at most to be kept within a certain limit, in order to avoid the confusion and intemperance of a multitude. In all very numerous assemblies, of whatever characters composed, passion never fails to wrest the scepter from reason. Had every Athenian citizen been a Socrates, every Athenian assembly would still have been a mob.
James Madison[I]n the next place, to show that unless these departments be so far connected and blended as to give to each a constitutional control over the others, the degree of separation which the maxim requires, as essential to a free government, can never in practice be duly maintained.
James Madison