irst the immediate literary context, the entire Second Amendment:
A well regulated militia, being necessary to the security of a free state, the right of the people to keep and bear arms, shall not be infringed.

The literary context provides the socio-cultural context of the Amendment, namely the American Revolution and establishment of new nation, one without a standing army. In that context, people owned the weapons they would use in defense of the common good. It is interesting to note that the original text is gender-inclusive in its form although we are still struggling over the role of armed women in combat.

The Revolutionary Era militia has been superseded by an Army and Navy, which spawned the Air Force (formerly Army Air Corps), and Marine Corps, now augmented by state and local police - which have their own colonial and pre-colonial predecessors, National Guard and Coast Guard. And in each case those women and men have their firearms supplied by the governments (local, state, federal) that employ them. The necessity met by a "well regulated militia" in the Revolutionary Era and its aftermath is now met without militias. The originating context of the Second Amendment no longer exists.