During the thirty-five years which elapsed after the recall of Agricola, until the reign of the Emperor Hadrian, the Roman historians, from whom alone we derive our information, hardly deign to notice the island; while, as is well known, no native records, or even what might perhaps have been a copy of a native record, have come down to us: indeed, it may be seriously doubted whether letters were at all generally known beyond the schools of the Druids. There is, however, every reason to suppose that the Britons pursued with persevering industry those commercial occupations we have already named; that the advice and example of Agricola had not been given in vain, or neglected on his departure; and, that, long ere that time, trade and commerce must have taken deep root in the island, as the city of London had even then given tokens of its aptitude to become the mercantile capital of the world.[455] The pearl fisheries, abandoned afterwards from the inherent defects of British pearls, were developed to an extent hitherto unknown; and a trade was opened out in oysters, which were actually conveyed, probably by one of the overland routes, to Rome, to satisfy the cravings of the epicures of the imperial city. Indeed, they were in such demand as to form a subject for the poet’s satire. “Could at one bite the oyster’s taste decide, And say if at Circæan rocks, or in The Lucrine lake, or on the coasts of Richborough, In Britain, they were bred.”[456] Another extensive trade, the manufacture of baskets, is casually mentioned, in the same strain of wit, by another Roman poet in the following lines:— “Work of barbaric art, a basket, _I_ From painted Britain came, but the Roman city Now call the painted Britons’ art their own.”[457] [Sidenote: The Caledonian incursions.] We also learn, incidentally,[458] that the people of the northern part of Scotland, although the shores swarmed with fish, did not eat them, but subsisted entirely by hunting and on the fruits of the earth.