Comparison of his thoughts to Pearls

WIth open shells in seas, on heavenly dew,
A shining Oyster lusciously doth feed,
And then the birth of that aethereall seed
Shews when conceiv'd if Skies looke dark or blew:
So do my thoughts (Coelestiall twins) of you,
At whose aspect they first begin and breed,
When they came forth to light, demonstrate true
If ye then smil'd: or lowr'd in mourning weed
Pearles then are orient fram'd, and faire in forme
If heavens in their conceptions do look cleare:
But if they thunder, or do threat a storme.
They sadly darke and cloudy do appeare;
Right so my thoughts, and so my notes do change,
Sweet if ye smile, and hoarse if ye look strange.