Vimes struggled to his feet, shook his head and set off after it. No thought was involved. It is the ancient instinct of terriers and policemen to chase anything that runs away.
Terry PratchettFirst Thoughts are the everyday thoughts. Everyone has those. Second Thoughts are the thoughts you think about the way you think. People who enjoy thinking have those. Third Thoughts are thoughts that watch the world and think all by themselves. Theyโre rare, and often troublesome. Listening to them is part of witchcraft.
Terry Pratchett