Traffic was being held up by a crowd of people rushing across the road and by curious onlookers in cars, slowing down to gawk at something.

“Look, see the thief,” Kamali said.

It was a sight of old Africa, a naked man running alone down an embankment and splashing across a filthy creek, pursued by a mob.

“They have taken his clothes. He is trying to get away in the dirty water of the river.”

But he was surrounded. People lined both banks of the creek, holding sticks and boulders, laughing excitedly at the man, who was so panicked he did not even think to cover his private parts but just ran, his arms pumping, splashing in the disgusting muck.

I had forgotten how cheerful, even jubilant, such murderous crowds in Africa could be, particularly these spontaneous mobs in pursuit of a weak marked man trying in vain to flee — a thief, a political outcast, a member of a despised tribe. The isolation of such prey vitalized the pursuers and made them shout with joy as they went after him, the toughest men swaggering at the front, the older men cheering them on, the women ululating, the small children screeching and jumping up and down at the sight of all this motion. The vigor, the macabre good humor of the chase, and the idea of certain death were intoxicants. Years before, I had seen similar mobs in Malawi and Uganda, always a large number of excited people persecuting one or two victims. Then, what had frightened me most was the mob’s sense of fun. Fun was still a factor in massacre. Perhaps the reason was simple: weak, idle people, suddenly granted power and the opportunity blamelessly to beat someone to death, are given a snorting animal energy and become joyous in their triumph.

The laughing crowd surged toward the naked man, swinging sticks.

“They will kill him,” Kamali said.

Then the traffic began to move.

Paul Theroux, from Dark Star Safari