In this subtle sentence, the landowners' "benighted state of mind" is lumped together with mountains and coastline as "natural barriers" in Sir John's mind, showing how material progress begins with the conquest of nature but slides into the conquest of men. And not merely men, but men's "state of mind," suggesting that the struggle for rulership is essentially a struggle of dream-ideal vs. dream-ideal.

The meaning is heightened by the symbolism, in which mountains represent the ideal, clouds represent idealistic crusades, and the ever-calm gulf represents the fundamental isolation of man from man. The symbolism, embodying eternal concepts, lends deeper resonance to Sir John's casual "for ages."