Give a brief description of the Malay sequence in Opium Eater.

By the time of the Malay sequence, De Quincey has become hopelessly addicted to opium. Yet at the same time he's managed to reduce his dosage substantially, and proudly proclaims this year—1816—to be the happiest of his life.
One day, a Malayan sailor knocks at the door of De Quincey's cottage. He is a strange, exotic man in "dingy" pants. Not unreasonably, De Quincey wonders how and why a sailor from the other side of the world should suddenly turn up at the doorstep of a remote English country cottage. But he's unable to get any information out of his unusual visitor as the sailor doesn't speak a word of English.
Nonetheless, De Quincey proceeds to treat his unexpected guest to some unorthodox hospitality by giving him a piece of his opium stash. The sailor wolfs down the drugs in one go, leading De Quincey to fear that he might have an overdose. All seems well, however, as the Malay leaves the cottage without displaying any notable side-effects of his rash indulgence.
Whether the anecdote about the Malayan sailor is a true story, or just a drug-induced hallucination, is unclear. However, the incident has a profound effect upon De Quincey's fevered imagination, causing him to experience numerous terrifying nightmares.