All that mankind had ever written or dreamed about the Mediterranean, the doctor had in his library and could repeat to his eager little listener.  In Ferragut’s estimation the mare nostrum ["Mare Nostrum” (Our Sea), the classic name for the Mediterranean.] was a species of blue beast, powerful and of great intelligence—­a sacred animal like the dragons and serpents that certain religions adored, believing them to be the source of life.  The rivers that threw themselves impetuously into its bosom in order to renew it were few and scanty.  The Rhone and the Nile appeared to be pitiful little rivulets compared with the river courses of other continents that empty into the oceans.

Losing by evaporation three times more liquid than the rivers bring to it, this sunburnt sea would soon have been converted into a great salt desert were not the Atlantic sending it a rapid current of renewal that was precipitated through the Straits of Gibraltar.  Under this superficial current existed still another, flowing in an opposite direction, that returned a part of the Mediterranean to the ocean, because the Mediterranean waters were more salt and dense than those of the Atlantic.  The tide scarcely made itself felt on its strands.  Its basin was mined by subterranean fires that were always seeking extraordinary outlets through Vesuvius and Aetna and breathed continually through the mouth of Stromboli.  Sometimes these Plutonic ebullitions would come to the surface, making new islands rise up upon the waters like tumors of lava.

In its bosom exist still double the quantity of animal species that abound in other seas, although less numerous.  The tunny fish, playful lambs of the blue pasture lands, were gamboling over its surface or passing in schools under the furrows of the waves.  Men were setting netted traps for them along the coasts of Spain and France, in Sardinia, the Straits of Messina and the waters of the Adriatic.  But this wholesale slaughter scarcely lessened the compact, fishy squadrons.  After wandering through the windings of the Grecian Archipelago, they passed the Dardanelles and the Bosphorus, stirring the two narrow passageways with the violence of their invisible gallopade and making a turn at the bowl of the Black Sea, swimming back, decimated but impetuous, to the depths of the Mediterranean.

Red coral was forming immovable groves on the substrata of the Balearic Islands, and on the coasts of Naples and Africa.  Ambergris was constantly being found on the steep shores of Sicily.  Sponges were growing in the tranquil waters in the shadow of the great rocks of Mallorca and the Isles of Greece.  Naked men without any equipment whatever, holding their breath, were still descending to the bottom as in primitive times, in order to snatch these treasures away.