They know not my heart, who believe there can be
One stain of this earth in its feelings for thee;
Who think, while I see thee in beauty's young hour,
As pure as the morning's first dew on the flower,
I could harm what I love, -- as the sun's wanton ray
But smiles on the dew-drop to waste it away.

No -- beaming with light as those young features are,
There's a light round thy heart which is lovelier far:
It is not that cheek -- 'tis the soul dawning clear
Through its innocent blush makes thy beauty so dear:
As the sky we look up to, though glorious and fair,
Is look'd up to the more, because Heaven lies there!

Thomas Moore

http://www.poemhunter.com/poem/they-know-not-my-heart/