Laurentius lived at Haarlem and was a man of property. He seems to have been engaged in printing books from wood blocks or plates, well known to antiquaries as the _Block Books_, in which the reading matter was illustrated by rude pictures. Fragments of works so printed by him are still in existence. Among others, the celebrated _Biblia Pauperum_, executed between 1410 and 1420, has been attributed to him. It was only natural that his thoughts should be led to the production of single types, as a means of cheapening and facilitating his work. These were first made of wood, and afterward of tin. The date of his invention of separate types is given as about the year 1429. Other dates have been stated, ranging from 1422 to 1436. The first of his printed books, it is claimed, was the _Speculum Humanæ Salvationis_, of which about ten copies are now known to be in existence. A small primer, or _Abecedarium_, in our opinion, shows all the marks of the first attempt of an experimenter in a new art. Koster died in 1439. The necessity for employing workmen to assist in prosecuting the art led to the divulging of the secret. Among these men, it is supposed, was John Geinsfleisch, (or Gutenberg, Senior,) who, after learning the processes, returned to Mentz, his native place, and communicated the secret to his nephew, John Gutenberg, an ingenious artist of Strasburg. It is in evidence that the latter, in connection with two partners, spent a considerable amount of money in some private experiments. These appear to have occupied several years, from 1436 to 1439, when a legal contest arose as to the rights of one of the partners whose zealous activity had caused his death. Gutenberg continued at Strasburg till 1444, when, his means being exhausted, he rejoined his uncle at Mentz. Here he renewed his experiments, and, needing money, he procured an introduction to John Fust, a capitalist and money-lender, who seems to have been struck with the importance of the work, and who advanced a considerable amount (all the tools and presses being pledged as security) in furtherance of the enterprise. Two years were occupied in making the types and necessary machinery, when the great work of printing the Bible was begun. There can be little doubt that, during all his years of experiment, Gutenberg had executed smaller books, one of which is surmised to have been a reproduction of the Dutch _Speculum_ of Koster. The _Donatus_ of 1451, the _Appeal against the Turks_ of 1454, and the _Letters of Indulgence_ of 1454 and 1455, all appeared before the Bible,[2] which was not published till 1455 or 1456. This great book marked an era in the art.[3] It is painful to be told that about this time Fust foreclosed the mortgage, and the entire work with all the materials passed into his possession. It seems, however, that Gutenberg succeeded in re-establishing a press, and continued to practise the art, but produced no work at all comparable with the Bible. He died about 1468.