check out our:
"Another report from the cliff made me think suddenly of that ship of war I had seen firing into a continent. It was the same kind of ominous voice; but these men could by no stretch of imagination be called enemies. They were called criminals and the outraged law, like the bursting shells, had come to them, an insoluble mystery from over the sea. All their meager breasts panted together, the violently dilated nostrils quivered, the eyes stared stonily up-hill. They passed me within six inches, without a glance, with that complete, deathlike indifference of unhappy savages." (1.36)
It's a mad, mad, mad world: the chained slaves are so beaten down that they don't even notice their surroundings. They're the opposite of dangerous enemies—in fact, it's the Europeans who are the dangerous enemies.
"I avoided a vast artificial hole somebody had been digging on the slope, the purpose of which I found it impossible to divine. It wasn't a quarry or a sandpit, anyhow. It was just a hole. It might have been connected with the philanthropic desire of giving the criminals something to do. I don't know. Then I nearly fell into a very narrow ravine, almost no more than a scar in the hillside." (1.38)
This random hole is another sign that people go crazy in the wilderness. (Maybe it's aliens?) But it isn't harmless eccentricity—when Marlow almost falls into another little ravine, we get the feeling that the madness is getting dangerous.
"He had come out for a moment, he said, 'to get a breath of fresh air. The expression sounded wonderfully odd, with its suggestion of sedentary desk-life." (1.43)
Wait, if you're actually living in the wilderness in a hut, why do you need to come outside for air? It's as though the accountant is trying to live the same kind of life he'd be living back in Brussels—which sounds pretty crazy to us.