When they look up to the sun,
Curse the toil by which he drew
The treasure from its bed of blue."
Costly as pearls are, they are merely the calcareous production of Mollusks. Diamonds have elsewhere been shown to be merely charcoal; the pearl is little else but concentric layers of membrane and carbonate of lime. All Mollusks are instances of that beneficent law of nature, that the hard parts accommodate themselves to the soft. The common naked snail, the mussel, cockle, oyster, garden helix, strombus, and nautilus, elegant or rough, rare or common, each illustrate this grand law. The body of a soft consistence is enclosed in an elastic skin. From this skin calcareous matter is continually exuded. This protects the animal, and forms the shell. Where the waves are rough, and rocks superabundant, then the shell is rough, hard, stony, fit to weather anything; where only smooth water and halcyon days are to be looked for, Nature, which never works in vain, provides but paper sides and an egg-shell boat, such as the little nautilus navigates and tacks and steers in.
Besides forming the rough outside, the calcareous exuvium, the mucus of the oyster, and other mollusks, form that beautiful substance, so smooth and polished, and dyed with rainbow tints and a glorious opalescence, which, be it as common as luxury has made it, still charms the eye. This is the lining of the shell, the mother-of-pearl, nacre. "The inside of the shell," said old Dampier—that old sailor with a poet's mind—"is more glorious even than the pearl itself."
It is glorious; it has the look of the morning, and the tint of the evening sky; the colours of the prism chastened, softened, retained, and made perpetual in it: this is mother-o'-pearl.
To render its bed always soft and cosy, to lie warm, packed as one might at Malvern in wet sheets, seems to be the oyster's pleasure. This singular exuvium, this mucus, not only creates pleasure, but alleviates pain. Some irritating substance, some internal worry and annoyance, it may be a dead embryo, or a grain of sand insinuates itself, and, lo! the creature covers it with this substance to ease off its unkind tooth, and converts it into a pearl.
That is the way they are made, these wondrous gems! And very beautiful is the thought that the most highly prized of gems should be but the effect of a creature to ease off a sorrow. Every one knows Shakspeare's wondrously fine reflection upon the uses of sorrow and adversity, which,
"Like the toad, ugly and venomous,
Bears yet a precious jewel in its head."