The Maracot Deep by Sir Arthur Conan Doyle

I have already said that within a short distance of the underground dwelling of the Atlanteans, prepared beforehand to meet the catastrophe which overwhelmed their native land, there lay the ruins of that great city of which their dwelling had once been part. I have described also how with the vitrine bells charged with oxygen upon our heads we were taken to visit this place, and I tried to convey how deep were our emotions as we viewed it. No words can describe the tremendous impression produced by those colossal ruins, the huge carved pillars and gigantic buildings, all lying stark and silent in the grey phosphorescent light of the bathybian deeps, with no movement save the slow wash of the giant fronds in the deep-sea currents, or the flickering shadows of the great fish which passed through the gaping doors or flitted round the dismantled chambers. It was a favourite haunt of ours, and under the guidance of our friend Manda we passed many an hour examining the strange architecture and all the other remains of that vanished civilization which bore every sign of having been, so far as material knowledge goes, far ahead of our own.

I have said material knowledge. Soon we were to have proof that in spiritual culture there was a vast chasm which separated them from us. The lesson which we carry from their rise and their fall is that the greatest danger which can come to a state is when its intellect outruns its soul. It destroyed this old civilization, and it may yet be the ruin of our own.