Hadrianus Junius, who has held the noble reputation of being the most learned man in the Netherlands after Erasmus, was the first to give the full account of the legend of Koster in his Batavia, published posthumously in 1568. In addition to the above story of the initial idea and discovery, he relates how Koster then went on to experiment with block printing and improve the quality of ink employed (as the ink generally used by scribes tended to run when used in a press) and, with the help of his son-in-law, Thomas Pieter, produced the book Speculum Humanæ Salvationis, and then continued to improve his methods with various types of wood, then lead, and finally mixtures of lead and tin. Prospering with his invention, he hired a number of assistants, including one Johannes Faust. It was this Faust, as the story goes, who himself became adept at the art of printing and casting type, and who on Christmas Eve of 1441 then broke into his master's shop, stole all of his types and equipment, and fled to Amsterdam, then on to Cologne and, finally, to Mainz.