This is from a poem called "The Fisher's Boy," which is available on the Thoreau Reader site:
The Fisher's Boy
by Henry David Thoreau
My life is like a stroll upon the beach,
As near the ocean's edge as I can go;
My tardy steps its waves sometimes o'erreach,
Sometimes I stay to let them overflow.
My sole employment is, and scrupulous care,
To place my gains beyond the reach of tides, —
Each smoother pebble, and each shell more rare,
Which Ocean kindly to my hand confides.
I have but few companions on the shore:
They scorn the strand who sail upon the sea;
Yet oft I think the ocean they've sailed o'er
Is deeper known upon the strand to me.
The middle sea contains no crimson dulse,
Its deeper waves cast up no pearls to view;
Along the shore my hand is on its pulse,
And I converse with many a shipwrecked crew.
Lovely thoughts to take along to a maritime museum--to keep in mind when engaging with the items on exhibit.