Sir Thomas Elyot received little reward for his services to the state, but his scholarship and his books were held in high esteem by his contemporaries. The _Boke named the Governour_ was printed by Thomas Berthelet (1531, 1534, 1536, 1544, &c.). It is a treatise on moral philosophy, intended to direct the education of those destined to fill high positions, and to inculcate those moral principles which alone could fit them for the performance of their duties. The subject was a favourite one in the 16th century, and the book, which contained many citations from classical authors, was very popular. Elyot expressly acknowledges his obligations to Erasmus's _Institutio Principis Christiani_; but he makes no reference to the _De regno et regis institutione_ of Francesco Patrizzi (d. 1494), bishop of Gaeta, on which his work was undoubtedly modelled. As a prose writer, Elyot enriched the English language with many new words. In 1534 he published _The Castell of Helth_, a popular treatise on medicine, intended to place a scientific knowledge of the art within the reach of those unacquainted with Greek. This work, though scoffed at by the faculty, was appreciated by the general public, and speedily went through many editions. His Latin _Dictionary_, the earliest comprehensive dictionary of the language, was completed in 1538. The copy of the first edition in the British Museum contains an autograph letter from Elyot to Thomas Cromwell, to whom it originally belonged. It was edited and enlarged in 1548 by Thomas Cooper, bishop of Winchester, who called it _Bibliotheca Eliotae_, and it formed the basis in 1565 of Cooper's _Thesaurus linguae Romanae et Britannicae_.