The last line of this scroll is what makes it famous. Translated, it says that it was reverently made for universal free distribution by Wang Jie, on behalf of his two parents, on a day that converts to 11 May 868. That is a printer, a date, a purpose and a dedication, in a printed book, six centuries before Gutenberg.
The purpose is the part usually skipped. This was not a commercial edition. In Buddhist practice, reproducing a sutra generates merit, and the merit can be dedicated to someone else, which is exactly what Wang Jie says he is doing for his parents. Woodblock printing made it possible to generate that merit at scale, and the earliest surviving dated printed book in the world is therefore not a product but an offering.
The object is a roll of about five metres, seven printed sheets pasted end to end, opening with a printed frontispiece that shows the Buddha addressing the monk Subhuti. The quality of the cutting is high and confident, which is itself evidence: nobody produces work of this standard at a first attempt, so printing in China must already have been established for some time before 868. What survives is the earliest dated example, not the earliest example, and undated printed fragments from Korea and Japan are argued to be older still.
The text it carries suits the object. The Diamond Sutra is short, it was among the most copied of all Mahayana scriptures, and it ends by commending precisely the act of reproducing and passing it on. A printer looking for the first thing worth cutting into blocks at length could hardly have chosen better.