Up to the years around the 1870's, Japanese books were generally printed by means of woodblocks with letters carved on them. Naturally it was a slow process and large number of copies were not to be expected. Seiyo Jijo (Things Western), one of Fukuzawa Yukichi's representative publications, was composed of four books-First Book, Extra Book, Second Book, and Third Book. It is said that more than 150,000 copies of the First Book alone were printed. The present author, who had some questions concerning this excessive number printed on woodblock, took up the comparison of various copies of Seiyo Jijo and discovered several new facts. It has been generally thought that the First Book and the Extra Book had their blocks remade three times and the other books twice, and no thought has been given to further classification of the copies. However, there are in fact several varieties of Seiyo Jijo which can be distinguished by their binding or by the lists of Keio-gijuku Shuppansha publications in the appendices. And it became possible to determine the order of publication for some of them; Also, it was discovered that there was one particular edition which bound two books in one. The new discovery makes it necessary to revise the previous idea that there was only one set of blocks for each edition, thus providing a new explanation for the unusually large number of copies printed.