Hitherto unknown documents from the Moravian archive Brno throw light on the story of the imperial chymicus Wenzel Seiler (1648-1681). Twenty letters from the Moravian Archive in Brno (Fasc. 44 / 137, G minus 7, source: monastery St. Thomas in Brno) enable us to reconstruct some episodes in his life. These documents cover the time from Seiler's flight from the cloister St. Thomas in Brno in December 1671 up to September 1673, when Seiler performed transmutational experiments in the presence of Emperor Leopold I in Vienna and applied for discharge from the Augustinian order. Today, a more-or-less satisfying curriculum vitae of this well-known alchemist can be issued. Johann Joachim Becher (Magnalia Naturae, 1680) reported that after his escape from the monastery, Seiler was taken directly from Brno to Castle Feldsberg (Valtice) by coach. In March 1672 the renegade monk together with his comrade Ernst Preihauser was at the court of Valtice. The first attempt to arrest him failed, since both alchemists quickly got to Vienna. Later Wenzel and Ernst were captured at Hartberg in Styria but both alchemists were able to get free again. During the following months both performed transmutations at the Viennese residences of Count Franz Ernst von Schlick and Count Franz Ernst von Paar. From the beginning of July 1672 forward, Count Frantz Augustin von Waldstein (Wallenstein, d.1684) supervised all of Seiler's experiments, at first at the estate of Laxemburg and later in the laboratory in Vienna. In June 1677 the Austrian ambassador at the court of King Charles II, Karl Ferdinand Count Waldstein (Wallenstein 1634-1702), gave a full account on Seiler to Robert Boyle. Seiler died in his laboratory, and his unexpected career allows us to draw a genre-painting of the attitude at the court of Leopold I towards an alchemy.