One of seven Spenserian sonnets appended to Sir Philip Sidney's Defense of Poetry. Doubtless Edward Thurlow is remembering the sonnets to aristocratic figures Edmund Spenser had appended to the first publication of the Faerie Queene in 1590.
Francis Rawdon Hastings (1754-1826) become the second Earl of Moira in 1793; like Sir Philip Sidney he had distinguished military career, beginning in the American war of Independence.
Horace Walpole to David Hume: "Allowing as much sense to Sir Philip as his warmest admirers can demand for him, surely this country has produced many men of far greater abilities, who have by no means met with a proportionate share of applause. It were a vain parade to name them — take Lord Bacon alone, who I believe of all our writers, except Newton, is most known to foreigners, and to whom Sir Philip was a puny child in genius, — how far was he from attaining an equal degree of fame and honour? To say the truth, I attribute the great admiration of Sir Philip Sidney to his having so much merit and learning for a man of his rank" 15 July 1758; in Letters, ed. Cunningham (1906) 3:151.
To thee, that art the glory of our days,
And patron of all princely gentleness,
This image of delight my Muse conveys,
To be accepted of thy nobleness;
That with thy favour Thou the same may'st bless,
And shield great Sidney from detracting wrong,
Sith his pure lines to purer ears express
All musick, both of wisdom, and of tongue;
And sith in his most sweet heroick song,
As in a mirror, thou may'st timely see
The virtues, that exempt thee from the throng,
And make thy life divinest poesy;
Therefore, great Lord, vouchsafe this book to take,
Both for its own, and for its Author's sake.