He was meditating out loud.

"Yes," he said, "the ocean owns a genuine circulation, and to start it going, the Creator of All Things has only to increase its heat, salt, and microscopic animal life. In essence, heat creates the different densities that lead to currents and countercurrents. Evaporation, which is nil in the High Arctic regions and very active in equatorial zones, brings about a constant interchange of tropical and polar waters. What's more, I've detected those falling and rising currents that make up the ocean's true breathing. I've seen a molecule of salt water heat up at the surface, sink into the depths, reach maximum density at -2 degrees centigrade, then cool off, grow lighter, and rise again. At the poles you'll see the consequences of this phenomenon, and through this law of farseeing nature, you'll understand why water can freeze only at the surface!"

As the captain was finishing his sentence, I said to myself: "The pole! Is this brazen individual claiming he'll take us even to that location?"

Meanwhile the captain fell silent and stared at the element he had studied so thoroughly and unceasingly. Then, going on:

"Salts," he said, "fill the sea in considerable quantities, professor, and if you removed all its dissolved saline content, you'd create a mass measuring 4,500,000 cubic leagues, which if it were spread all over the globe, would form a layer more than ten meters high. And don't think that the presence of these salts is due merely to some whim of nature. No. They make ocean water less open to evaporation and prevent winds from carrying off excessive amounts of steam, which, when condensing, would submerge the temperate zones. Salts play a leading role, the role of stabilizer for the general ecology of the globe!"

Captain Nemo stopped, straightened up, took a few steps along the platform, and returned to me:

"As for those billions of tiny animals," he went on, "those infusoria that live by the millions in one droplet of water, 800,000 of which are needed to weigh one milligram, their role is no less important. They absorb the marine salts, they assimilate the solid elements in the water, and since they create coral and madrepores, they're the true builders of limestone continents! And so, after they've finished depriving our water drop of its mineral nutrients, the droplet gets lighter, rises to the surface, there absorbs more salts left behind through evaporation, gets heavier, sinks again, and brings those tiny animals new elements to absorb. The outcome: a double current, rising and falling, constant movement, constant life! More intense than on land, more abundant, more infinite, such life blooms in every part of this ocean, an element fatal to man, they say, but vital to myriads of animals--and to me!"

When Captain Nemo spoke in this way, he was transfigured, and he filled me with extraordinary excitement.

"There," he added, "out there lies true existence! And I can imagine the founding of nautical towns, clusters of underwater households that, like the Nautilus, would return to the surface of the sea to breathe each morning, free towns if ever there were, independent cities! Then again, who knows whether some tyrant . . ."

Captain Nemo finished his sentence with a vehement gesture. Then, addressing me directly, as if to drive away an ugly thought:

"Professor Aronnax," he asked me, "do you know the depth of the ocean floor?"

"At least, captain, I know what the major soundings tell us."

"Could you quote them to me, so I can double-check them as the need arises?"

"Here," I replied, "are a few of them that stick in my memory. If I'm not mistaken, an average depth of 8,200 meters was found in the north Atlantic, and 2,500 meters in the Mediterranean. The most remarkable soundings were taken in the south Atlantic near the 35th parallel, and they gave 12,000 meters, 14,091 meters, and 15,149 meters. All in all, it's estimated that if the sea bottom were made level, its average depth would be about seven kilometers."

"Well, professor," Captain Nemo replied, "we'll show you better than that, I hope.