The day was ending in a serenity of still and exquisite brilliance. The water shone pacifically; the sky, without a speck, was a benign immensity of unstained light; the very mist on the Essex marshes was like a gauzy and radiant fabric, hung from the wooded rises inland, and draping the low shores in diaphanous folds. Only the gloom to the west, brooding over the upper reaches, became more somber every minute, as if angered by the approach of the sun.
And at last, in its curved and imperceptible fall, the sun sank low, and from glowing white, changed to a dull red without rays and without heat, as if about to go out suddenly, stricken to death by the touch of that gloom brooding over a crowd of men.
Forthwith a change came over the waters, and the serenity became less brilliant but more profound. The old river in its broad reach rested unruffled at the decline of day, after ages of good service done to the race that peopled its banks, spread out in the tranquil dignity of a waterway leading to the uttermost ends of the earth. We looked at the venerable stream not in the vivid flush of a short day that comes and departs for ever, but in the august light of abiding memories. (1.4-6)
Man, we just love sunsets. Everything is bathed in heavenly white light … oh, wait. Except the western horizon. We're thinking that maybe the West (as in Europe) isn't quite as enlightened as it thinks it is. Check out how the sunlight grows more sinister as it falls towards the western horizon, turning from a friendly white to a "dull red"—you know, like fire. And in case you think that this is just a description and not metaphorical or symbolic, Conrad tells us that they're watching the Thames in the "august light of abiding memories," i.e. that they're looking at it though the lens of all their past experiences.