The "blockhouse" image of San Tomé, a military one, aptly recurs here in the chapter where the mine becomes a military force. But the description is applied to the mountain itself, not to the "faint tracings" of the mine, so it also applies symbolically to the Ideal. "Cyclopean" suggests both gigantic (continuing the image of the mountains as a land of giants) and monocular; the two words together paint the Ideal as gigantic, single-minded, and militaristic.