“The defense of one’s self, justly called the primary law of nature, is not, nor can it be abrogated by any regulation of municipal law. This principle of defense is not confined merely to the person; it extends to the liberty and the property of a man … it extends to the person of every one, who is in danger; perhaps, to the liberty of every one, whose liberty is unjustly and forcibly attacked.” — James Wilson (1791)

For  a short and slightly inaccurate summary of decisional law based on the Second Amendment, please see:  http://constitution.findlaw.com/amendment2.html .  It does, however, get right that Heller revisited the right as belonging to individuals and not states.