I remember from Middle Ages 3 PL: 1. I was monk in medieval monastery and I dictated from memory sentences for two scribes. They wrote their to book. 2. In my workroom I produced substance. I tested miscellaneous procedures. I read from book and occasionally looked at me my wife. Eventually I managed to required substance. I remember at procedures only on red color of substance. I could be scientist or alchemist. 3. Third PL I will mention separately in future post.