Old books were full of it. Don’t know about this one but i remember reading bishop Thietmar chronicle (btw a fundamental work for early history of Poland), and every few pages he met some dead priest in a dream which would reveal some info, usually a pure rumour or dying regret. Basically supernatural gossip mill lol. Though to be fair the next bishop after reading probably felt so embarrassed that he hide the manuscript and so it survived. Also fortunately no dream figures talked to Thietmar about any real events, those he witnessd personally or talk with eyewitnesses.