A theorist as well as performer, the Lord Keeper Guilford enunciated his views regarding the principles of melody in 'A Philosophical Essay of Musick, Directed to a Friend'--a treatise that was published without the author's name, by Martin, the printer to the Royal Society, in the year 1677, at which time the future keeper was Chief Justice of the Common Pleas. The merits of the tract are not great; but it displays the subtlety and whimsical quaintness of the musical lawyer, who performed on several instruments, was very vain of a feeble voice, and used to attribute much of his professional success to the constant study of music that marked every period of his life. "I have heard him say," Roger records, "that if he had not enabled himself by these studies, and particular his practice of music upon his bass or lyra viol (which he used to touch lute-fashion upon his knee), to divert himself alone, he had never been a lawyer. His mind was so airy and volatile he could not have kept his chamber if he must needs be there, staked down purely to the drudgery of the law, whether in study or practice; and yet upon such a leaden proposition, so painful to brisk spirits, all the success of the profession, regularly pursued, depends." His first acquaintance with melodious art was made at Cambridge, where in his undergraduate days he took lessons on the viol. At this same period he "had the opportunity of practice so much in his grandfather's and father's families, where the entertainment of music in full concert was solemn and frequent, that he outdid all his teachers, and became one of the neatest violinists of his time." Scarcely in consistence with this declaration of the Lord Keeper's proficiency on the violin is a later passage of the biography, where Roger says that his brother "attempted the violin, being ambitious of the prime part in concert, but soon found that he began such a difficult art too late." It is, however, certain that the eminent lawyer in the busiest passages of his laborious life found time for musical practice, and that besides his essay on music, he contributed to his favorite art several compositions which were performed in private concert-rooms.