Rem actam agis.
(Plautus, Pseudolous 260)

Pron = rehm AHK-tahm AH-ghis

You are doing something (that has already been ) done.

Comment: This is either a scolding (you are doing something that's already been finished!), or this is a humbling reminder. As much as I love creative and ingenious activity, it reminds me that the vast majority of human activity is a repeat, a cycle, a circle, a pattern that we keep repeating. Until we learn. So that we can learn. So that we can point a finger and say: look, this is wisdom.

So, sitting around (our computers) and repeating proverbs is something that has been done before. :)