something to not do while working on your thesis

Do not open two copies of the same chapter of your thesis, make 2 hours worth or revisions on it, and then save the old version over the changes before closing the file. Furthermore, do not fail to notice this problem until 6 hours after said changes were made. It will make you think that you have actually gone crazy and that the beautiful new draft with eloquent rephrasings was entirely in your head.