It's pretty clear to me:
"I ask, sir, what is the militia? It is the whole people, except for a few public officials."
-- George Mason, in Debates in Virginia Convention on Ratification of the Constitution, Elliot, Vol. 3, June 16, 1788
"Whereas civil-rulers, not having their duty to the people duly before them, may attempt to tyrannize, and as military forces, which must be occasionally raised to defend our country, might pervert their power to the injury of their fellow citizens, the people are confirmed by the article in their right to keep and bear their private arms."
-- Tench Coxe, in Remarks on the First Part of the Amendments to the Federal Constitution
"The best we can hope for concerning the people at large is that they be properly armed."
-- Alexander Hamilton, The Federalist Papers at 184-188
"If the representatives of the people betray their constituents, there is then no recourse left but in the exertion of that original right of self-defense which is paramount to all positive forms of government, and which against the usurpations of the national rulers may be exerted with infinitely better prospect of success than against those of the rulers of an individual State. In a single State, if the persons entrusted with supreme power become usurpers, the different parcels, subdivisions, or districts of which it consists, having no distinct government in each, can take no regular measures for defense. The citizens must rush tumultuously to arms, without concert, without system, without resource; except in their courage and despair."
-- Alexander Hamilton, Federalist No. 28
"That the said Constitution shall never be construed to authorize Congress to infringe the just liberty of the press or the rights of conscience; or to prevent the people of the United States who are peaceable citizens from keeping their own arms ... "
-- Samuel Adams, Debates and Proceedings in the Convention of the Commonwealth of Massachusetts, at 86-87 (Pierce & Hale, eds., Boston, 1850)
"[The Constitution preserves] the advantage of being armed which Americans possess over the people of almost every other nation...(where) the governments are afraid to trust the people with arms."
--James Madison, The Federalist Papers, No. 46
"To suppose arms in the hands of citizens, to be used at individual discretion, except in private self-defense, or by partial orders of towns, countries or districts of a state, is to demolish every constitution, and lay the laws prostrate, so that liberty can be enjoyed by no man; it is a dissolution of the government. The fundamental law of the militia is, that it be created, directed and commanded by the laws, and ever for the support of the laws."
--John Adams, A Defense of the Constitutions of the United States 475 (1787-1788)
"Before a standing army can rule, the people must be disarmed; as they are in almost every kingdom in Europe. The supreme power in America cannot enforce unjust laws by the sword; because the whole body of the people are armed, and constitute a force superior to any band of regular troops that can be, on any pretense, raised in the United States. A military force, at the command of Congress, can execute no laws, but such as the people perceive to be just and constitutional; for they will possess the power, and jealousy will instantly inspire the inclination, to resist the execution of a law which appears to them unjust and oppressive."
--Noah Webster, An Examination of the Leading Principles of the Federal Constitution (Philadelphia 1787).
"Who are the militia? Are they not ourselves? Is it feared, then, that we shall turn our arms each man against his own bosom. Congress have no power to disarm the militia. Their swords, and every other terrible implement of the soldier, are the birthright of an American...[T]he unlimited power of the sword is not in the hands of either the federal or state governments, but, where I trust in God it will ever remain, in the hands of the people."
--Tenche Coxe, The Pennsylvania Gazette, Feb. 20, 1788.
"Whereas, to preserve liberty, it is essential that the whole body of the people always possess arms, and be taught alike, especially when young, how to use them; nor does it follow from this, that all promiscuously must go into actual service on every occasion. The mind that aims at a select militia, must be influenced by a truly anti-republican principle; and when we see many men disposed to practice upon it, whenever they can prevail, no wonder true republicans are for carefully guarding against it."
--Richard Henry Lee, The Pennsylvania Gazette, Feb. 20, 1788.
"What country can preserve its liberties if its rulers are not warned from time to time that their people preserve the spirit of resistance? Let them take arms."
-- Thomas Jefferson to William Stephens Smith, 1787. ME 6:373, Papers 12:356
"No Free man shall ever be debarred the use of arms."
-- Thomas Jefferson, Proposal Virginia Constitution, 1 T. Jefferson Papers, 334,[C.J. Boyd, Ed., 1950]
"The right of the people to keep and bear ... arms shall not be infringed. A well regulated militia, composed of the body of the people, trained to arms, is the best and most natural defense of a free country ..."
-- James Madison, I Annals of Congress 434, June 8, 1789
"What, Sir, is the use of a militia? It is to prevent the establishment of a standing army, the bane of liberty .... Whenever Governments mean to invade the rights and liberties of the people, they always attempt to destroy the militia, in order to raise an army upon their ruins."
-- Rep. Elbridge Gerry of Massachusetts, spoken during floor debate over the Second Amendment, I Annals of Congress at 750, August 17, 1789
" ... to disarm the people - that was the best and most effectual way to enslave them."
-- George Mason, 3 Elliot, Debates at 380
" ... but if circumstances should at any time oblige the government to form an army of any magnitude, that army can never be formidable to the liberties of the people, while there is a large body of citizens, little if at all inferior to them in discipline and use of arms, who stand ready to defend their rights ..."
-- Alexander Hamilton speaking of standing armies in Federalist 29
"Are we at last brought to such humiliating and debasing degradation, that we cannot be trusted with arms for our defense? Where is the difference between having our arms in possession and under our direction, and having them under the management of Congress? If our defense be the real object of them under the management of Congress? If our defense be the real object of having those arms, in whose hands can they be trusted with more propriety, or equal safety to us, as in our own hands?"
-- Patrick Henry, 3 J. Elliot, Debates in the Several State Conventions 45, 2d ed. Philadelphia, 1836
"The great object is, that every man be armed ... Every one who is able may have a gun."
-- Patrick Henry, Elliot, p.3:386
"O sir, we should have fine times, indeed, if, to punish tyrants, it were only sufficient to assemble the people! Your arms, wherewith you could defend yourselves, are gone ..."
-- Patrick Henry, Elliot p. 3:50-53, in Virginia Ratifying Convention demanding a guarantee of the right to bear arms
"The people are not to be disarmed of their weapons. They are left in full possession of them."
-- Zacharia Johnson, delegate to Virginia Ratifying Convention, Elliot, 3:645-6
"Certainly one of the chief guarantees of freedom under any government, no matter how popular and respected, is the right of citizens to keep and bear arms ... The right of citizens to bear arms is just one guarantee against arbitrary government, one more safeguard, against the tyranny which now appears remote in America but which historically has proven to be always possible."
-- Hubert H. Humphrey, Senator, Vice President, 22 October 1959
"The militia is the natural defense of a free country against sudden foreign invasions, domestic insurrections, and domestic usurpation of power by rulers. The right of the citizens to keep and bear arms has justly been considered, as the palladium of the liberties of the republic; since it offers a strong moral check against the usurpation and arbitrary power of rulers; and will generally ... enable the people to resist and triumph over them."
-- Joseph Story, Supreme Court Justice, Commentaries on the Constitution of the United States, p. 3:746-7, 1833
" ... most attractive to Americans, the possession of arms is the distinction between a freeman and a slave, it being the ultimate means by which freedom was to be preserved."
-- James Burgh, 18th century English Libertarian writer, Shalhope, The Ideological Origins of the Second Amendment, p.604
"The right [to bear arms] is general. It may be supposed from the phraseology of this provision that the right to keep and bear arms was only guaranteed to the militia; but this would be an interpretation not warranted by the intent. The militia, as has been explained elsewhere, consists of those persons who, under the laws, are liable to the performance of military duty, and are officered and enrolled for service when called upon.... [I]f the right were limited to those enrolled, the purpose of the guarantee might be defeated altogether by the action or the neglect to act of the government it was meant to hold in check. The meaning of the provision undoubtedly is, that the people, from whom the militia must be taken, shall have the right to keep and bear arms, and they need no permission or regulation of law for the purpose. But this enables the government to have a well regulated militia; for to bear arms implies something more than mere keeping; it implies the learning to handle and use them in a way that makes those who keep them ready for their efficient use; in other words, it implies the right to meet for voluntary discipline in arms, observing in so doing the laws of public order."
-- Thomas M. Cooley, General Principles of Constitutional Law, Third Edition 
"And that the said Constitution be never construed to authorize Congress ... to prevent the people of the United States, who are peaceable citizens, from keeping their own arms.... "