'TIS NOT thy flowing hair of orient gold,
Nor those bright eyes, like sapphire gems that glow;
Nor cheek of blushing rose, nor breast of snow,
The varying passions of the heart could hold:
Those locks, too soon, shall own a silv'ry ray,
Those radiant orbs their magic fires forego;
Insatiate TIME shall steal those tints away,
Warp thy fine form, and bend thy beauties low:
But the rare wonders of thy polish'd MIND
Shall mock the empty menace of decay;
The GEM, that in thy SPOTLESS BREAST enshrin'd,
Glows with the light of intellectual ray;
Shall, like the Brilliant, scorn each borrow'd aid,
And deck'd with native lustre NEVER FADE!
Mary Darby Robinson
http://www.poemhunter.com/poem/sonnet-inscribed-to-her-grace-the-duchess-of-dev/