The Mason Triad Context of Second Amendment Development and Purpose

Placing the Second Amendment into its appropriate Mason Triad period context as a barrier against government power greatly clarifies its meaning. It was never intended to protect state militia authority because its predecessors were understood as barriers to the power of the states. Instead, its purpose was to assure the people's control over the new Federal Government they authorized and any forces it might raise. This information fully explains the Second Amendment's references to a free state and the necessity of an effective militia of the people, who would be able to self-embody for organized defense with their own arms,because their right to possess and use arms was protected against any meddling by the government. 

Go read tthe whole thing.

This is one of the best explanations I have read for the 2nd Amendment.