It was March 12 of the year 1455 when Enea Silvio Piccolomini, future Pope Pius II, in a letter to Cardinal Juan de Carvajal, noted that he had seen some printed five-sheets in Frankfurt: well, it was precisely the specimens belonging to the circulation of the B42, better known as the ‘Gutenberg Bible’ and commonly considered the first printed text, although no sheet of any of the copies that have been received, or of those no longer in our possession, but of which we have news from other sources, bear date of print and / or name of the printer. Piccolomini’s missive is a fundamental dating element: it constitutes, in fact, the terminus ante quem for which we can say that the printing of the Bible occurred between 1452 and 1454. Its realization, happily ascribed to the name of Gutenberg, was however the result of a a real economic enterprise, which saw Johannes Gustfisch Gutenberg (who in fact was its creator), Johannes Fust (financier) and Peter Schöffer (engraver and calligrapher) united in a society. It was printed in two folio volumes of about 300 sheets each, for a total of 1286 pages and the use of 299 types (according to G. Zedler’s calculations). There are many hypotheses concerning the circulation: probably, 150 copies were printed in paper and 30-35 in parchment. Today, 49 copies survive from this original circulation, of which 37 on paper and 12 on parchment, and only the copy kept in Oxford is complete with all the cards, including the white ones on guard. From the analysis of surviving copies, some scholars have prepared a calculation of the workers and times of preparation of the Bible: about twenty people were employed for six months of work. The name of B42 derives precisely from one of the structural features of the Gutenberg Bible, printed in two columns of 42 lines. In reality, also in this sense, the Bible was a true typographic experiment: it presents in the initial sheets columns of 40 lines, then of 41 and only later of 42. The motivation for this change in the course of the work is more than never close to the needs of today’s publishing industry: the problem of editorial costs, so they tried to save paper by restricting the number of lines. Nor is it a coincidence that to be printed was precisely the text of the Bible in the Latin version (Vulgate) developed by St. Jerome in the fourth century, one of the few international texts and easily sold on a large scale. The reception area of the printed Bible had to be first of all the academic environment, therefore the theological and scholastic institutes in general, whose waiting horizon responded to demands of uniformity and textual correctness. No guarantee of uniformity was greater than that of mass production: so the B42 was a publishing success, and today, declared a UNESCO World Heritage Site, is the face of one of the greatest innovations that history has ever known: movable type printing.