The number of booksellers increased considerably in the course of the seventeenth century. The increase in their numbers is clearly shown in the Thesaurus 1473-1800, which contains the names of booksellers who also acted as publishers. In Amsterdam the number rose from five in the year 1585 to 102 in 1725; in The Hague it rose from 0 to 34; in Leiden from 8 to 23; Then there were those who did not have their own publications to sell but who, in some way, sold books of others. According to Gregorio Leti there were in Amsterdam, in 1690, more than one hundred bookshops, large, medium and small. All those who in some way earned their living from the publishing, selling and binding of books and other printed matter were associated, in the larger towns, in the local booksellers' guild. The number of members of the guilds was therefore higher than the number of bookseller-publishers mentioned in the Thesaurus. Thus, in 1700, the Amsterdam booksellers' guild had no less than 189 paying members.
As the number of booksellers grew, a certain degree of specialisation within the book trade occurred. More and more booksellers focused on the trade and selling of certain genres of publications. In towns with a university or an illustrious school, there was sufficient clientele to support an academic bookshop. In ports such as Amsterdam and Rotterdam, of course, a demand for shops with a wide range of manuals on seamanship, charts and atlases existed. As the Republic allowed various religious movements, there were also booksellers who focused on the various religious groups and shops could therefore be found that specialised in Reformed, Lutheran, Catholic, Socinian or Jewish publications. In the larger towns there was also interest in shops offering books in specific languages and in traders in prints.
Besides this normal trade by members of the booksellers' guild, a lively trade also existed in small printed matter distributed by pedlars and hawkers. They sold mostly pamphlets, songbooks, almanacs and devotional works. They were often only admitted in the towns during carnivals and annual fairs. This itinerant trade has left little documentary evidence. There are, however, a number of illustrations of hawkers.
