"Music and Poetry have ever been acknowledged Sisters, which walking hand in hand supports each other; As Poetry is the harmony of Words, So Musick is that of Notes: and as Poetry is a Rise above Prose and Oratory, so is Musick the exaltation of Poetry. Both of them may excel apart, but sure they are most excellent when they are joyn'd because nothing is then wanting to either of their Perfections: for thus they appear like Wit and Beauty in the same Person. Poetry and Painting have arriv'd to their perfection in our own Country: Musick is yet but in its Nonage, a forward Child which gives hope of what it may be hereafter in ENGLAND, when the Masters of it shall find more Encouragement. 'Tis now learning ITALIAN, which is its best Master, and studying a little of the French Air, to give it somewhat more of Gayety and Fashion. Thus being farther from the Sun, we are of later Growth than our Neighbour Countries, and must be content to shake off our Barbarity by degrees. The present Age seems already dispos'd to be refin'd, and to distinguish betwixt wild Fancy, and a just, numerous Composition. So far the Genius of your Grace has already prevail'd on Us. Many of the Nobility and Gentry have followed your Illustrious Example in the Patronage of Musick. Nay, even our Poets begin to grow asham'd of their harsh and broken Numbers, and promise to file our uncouth Language into smoother Words. Once more, therefore, I presume to offer Myself and this Composition with all humility to Your Grace's Protection, at least till I can redeem so mean a Present by One which may better deserve Your Acceptation. Be pleas'd to pardon my Ambition, which had no other means to obtain the Honour of being made known to You, but only this. The Town, which has been so indulgent to my first Endeavours in this kind, has encourag'd me to proceed in the same Attempt; and Your Favour to this Trifle will be a good Omen not only to the Success of the Next, but also to all the future Performances of Your Grace's most Obedient and most Obliged Servant, "HENRY PURCELL." The music of _Dioclesian_ is scored for "1st Violins, 2nd Violins, Tener Violins, Base Violins, 2 Flutes, 3 Hautboys (1st, 2nd, and Tener), 1 Basoon and 2 Trumpets;" the vocal parts have solos for all the voices, and there are numerous choruses. It is evident Purcell regarded this work with some affection and pride; all the printed copies were corrected by his own hand. At the end of the book is printed the following:-- "Advertisement. In order to the speedier Publication of this Book, I employed two several Printers; but One of them falling into some trouble, and the Volume swelling to a Bulk beyond my expectation, have been the Occasions of this Delay.