[pretzel]

Try using git blame. It tells you what change caused a line to happen. I often use it to find out exactly what issue caused a seemingly crazy bit of code to happen. As the code goes away, so does the commit message - not necessarily so with a comment.

[tomswartz07]

While that's true; `git pickaxe` will also do what you describe. The added bonus is that one could use pickaxe to follow a specific line's changes way farther back than a normal comment.

http://jfire.io/blog/2012/03/07/code-archaeology-with-git/