[kevinventullo]

I dunno, a common refrain I heard across all fields of math in grad school was “This is obvious. Wait, is this obvious…? Y… yes yeah it’s obvious. ”

[xelxebar]

It's actually an interesting observation. If you know where your keys are, finding them is trivial, but if you don't, then even the refrigerator becomes plausible.

Math does feel like that a lot of the time. Once you've tree-searched proof space and found the connection, you can usually spend way less time proving it the next time around.