Quite a few people have mistaken this quote for a reference to Douglas Adams. Cutwell had said. In the Disc model, Ankh-Morpork was a carbuncle. Alberto Malich, Founder of This University. I don't even remember walking under a mirror.
Superstition says that both walking under a ladder and breaking a mirror give bad luck.
Therefore, by the sort of skewed logic Terry continually gives to his characters, walking under a mirror must be really bad news. He remembered being summoned into reluctant existence at the moment the first creature lived, in the certain knowledge that he would outlive life until the last being in the universe passed to its reward, when it would then be his job, figuratively speaking, to put the chairs on the tables and turn all the lights off. When the last living thing dies, my job will be finished. I'll put the chairs on the tables, turn out the lights and lock the universe behind me when I leave. The APF is maintained by Leo Breebaart and Mike Kew , who always welcome corrections, questions or new annotations.