That I, wise for the final day,
Might measure time, like thee!

These were happy evenings--all the more happy from the circumstance that
I was still in heart and appetite a boy, and could relish as much as
ever, when their season came on, the wild raspberries of the Conon
woods--a very abundant fruit in that part of the country--and climb as
lightly as ever, to strip the guean-trees of their wild cherries. When
the river was low, I used to wade into its fords in quest of its pearl
muscles (_Unio Margaritiferus_); and, though not very successful in my
pearl-fishing, it was at least something to see how thickly the
individuals of this greatest of British fresh-water molluscs lay
scattered among the pebbles of the fords, or to mark them creeping
slowly along the bottom--when, in consequence of prolonged droughts, the
current had so moderated that they were in no danger of being swept
away--each on its large white foot, with its valves elevated over its
back, like the carpace of some tall tortoise. I found occasion at this
time to conclude, that the _Unio_ of our river-fords secretes pearls so
much more frequently than the _Unionidae_ and _Anadonta_ of our still
pools and lakes, not from any specific peculiarity in the constitution
of the creature, but from the effects of the habitat which it is its
nature to choose. It receives in the fords and shallows of a rapid river
many a rough blow from sticks and pebbles carried down in times of
flood, and occasionally from the feet of the men and animals that cross
the stream during droughts; and the blows induce the morbid secretions
of which pearls are the result. There seems to exist no inherent cause
why _Anadon Cygnea_, with its beautiful silvery nacre--as bright often,
and always more delicate than that of _Unio Margaritiferus_--should not
be equally productive of pearls; but, secure from violence in its still
pools and lakes, and unexposed to the circumstances that provoke
abnormal secretions, it does not produce a single pearl for every
hundred that are ripened into value and beauty by the exposed
current-tossed _Unionidae_ of our rapid mountain rivers. Would that
hardship and suffering bore always in a creature of a greatly higher
family similar results, and that the hard buffets dealt him by fortune
in the rough stream of life could be transmuted, by some blessed
internal predisposition of his nature, into pearls of great price.

It formed one of my standing