Brief Summary
The Set-Up
Public opinion has been gradually souring on liquor for a hundred years. It's time to get this thing done.
The Text
The 18th Amendment says you can't do anything with liquor other than drink it in your own home if you've already bought it. You either have liquor left over from when it was legal, or someone broke the law getting it to you, and you broke the law buying it.
The 21st Amendment says, "That 18th Amendment thing? Our bad. You can do all that, as long as your local laws say you can."
TL;DR
No drinking! Just kidding; drinking.