Schools open to the public may also have originated in Saxon times. In the medieval period-English universities, students often needed remedial instruction in elementary Latin grammar, while advanced Latin grammar formed part of the undergraduate course. Once pupils had mastered basic Latin, they continued their studies with texts in Latin itself. The difficult task of compiling an English dictionary with Latin equivalents was accomplished by a Dominican recluse of King's Lynn, who completed the work, called Promptorium parvulorum, in 1440. In the great lay households, boys and girls of the nobility and gentry were trained for lay careers rather than ecclesiastical ones, with greater emphasis on the vernacular than on Latin. When printed books became available in England, from English presses or through importation, large possibilities existed for selling educational books to noble households, and schools in towns and religious houses. Printers other than William Caxton sought to exploit the market in school text-books.