The much debated question whether Goethe was a member of the order [of the Illuminati] can now be affirmed with certainty. There was no known documentation that Goethe’s and Herder’s names were on the Illuminati rosters. However, the conclusion that both may have belonged to the order has always been justified that he and Karl August [Grand Duke of Saxe-Weimar-Eisenach], considering their close friendship and the well-known fact that the latter was an Illuminatus and Mason and the former a Freemason. The evidence for this was not known although it was found in the Gotha lodge archive. The said lodge has the order’s revers with Goethe’s signature and seal in its archive. The document shows as location and date: Weimar, February 11, 1783, having been issued and processed by Dr. Bode … on whose bidding, the Duke of Gotha and Prince August of Saxony, Goethe as well as Herder joined approximately during the same time period. There is no evidence that Goethe was an especially active participant in the order, and considering the prohibitions which would soon be enacted, this is also unlikely. His interest and allegiance to the order most likely faded, while he maintained his activities in Freemasonry.
~~Leopold Engel, Geschichte des Illuminaten-Ordens (1906)