The first object of a free people is the preservation of their liberty; and liberty is only to be preserved by maintaining constitutional restraints and just divisions of political power. Nothing is more deceptive or more dangerous than the pretence of a desire to simplify government. The simplest governments are despotism; the next simplest, limited monarchies; but all republics, all governments of law, must impose numerous limitations and qualifications of authority and give many positive and many qualified rights. In other words, they must be subject to rule and regulation. This is the very essence of free political institutions.
The spirit of liberty is, indeed, a bold and fearless spirit; but it is also a sharp-sighted spirit; it is a cautious, sagacious, discriminating, far-seeing intelligence; it is jealous of encroachment, jealous of power, jealous of man. It demands checks; it seeks for guards; it insists on securities; it intrenches itself behind strong defences, and fortifies itself with all possible care against the assaults of ambition and passion. It does not trust the amiable weaknesses of human nature, and therefore it will not permit power to overstep its prescribed limits, though benevolence, good intent, and patriotic purpose come along with it. Neither does it satisfy itself with flashy and temporary resistance to illegal authority. Far otherwise. It seeks for duration and permanence. It looks beforeand after; and, building on the experience of ages which are past, it labors diligently for the benefit of ages to come.
This is the nature of constitutional liberty; and this is our liberty, if we will rightly understand and preserve it.
Every free government is necessarily complicated, because all such governments establish restraints, as well on the power of government itself as on that of individuals. If we will abolish the distinction of branches, and have but one branch; if we will abolish jury trials, and leave all to the judge; if we will then ordain that the legislator shall himself be that judge; and if we will place the executive power in the same hands, we may readily simplify government. We may easily bring it to the simplest of all possible forms, a pure despotism. But a separation of departments, so far as practical, and the preservation of clear lines of division between them, is the fundamental idea in the creation of all our constitutions; and, doubtless, the continuance of regulated liberty depends on maintaining these boundaries.
From a speech in the U.S. Senate, May 7, 1834