Luther's disappearance during his return trip back to Wittenberg was planned. Frederick III had him intercepted on his way home in the forest near Wittenberg by masked horsemen who were made to appear as armed highwaymen. They escorted Luther to the security of the Wartburg Castle at Eisenach. During his stay at Wartburg, which he referred to as "my Patmos", Luther translated the New Testament from Greek into German and poured out doctrinal and polemical writings. These included a renewed attack on Archbishop Albrecht of Mainz, whom he shamed into halting the sale of indulgences in his episcopates, and a "Refutation of the Argument of Latomus," in which he expounded the principle of justification to Jacobus Latomus, an orthodox theologian from Louvain.