There is a traditional narrative in Estonia on how oil shale was first mentioned by A. W. Hupel in 1777 and how supposedly, A. J. Guldenstadt stated in his books that oil shale was discovered near Johvi in 1725. However, from historical literature and archival documents the authors of the present research found no evidence to prove these statements of the narrative. In this study, it will be specified how oil shale was actually discovered on the Kohala estate and first described in 1791.