As I continue reading A Dream of Red Mansions, one of the things that I've found interesting is the regular mention of 'sacrificial money' (in the translation I am reading). This is a very common Eastern cultural practice that is almost nonexistent in the West, so I was curious about it.
The more common name for it is 'joss paper'. It is easily burnable paper that is made to look like money, in many cases, although it can take many other forms. (Very popular examples, which can be ordered from paper offering stores, are paper 'credit cards', coins, and gold and silver ingots of paper foil, but anything luxurious that you can make a paper imitation of is fair game, and people have made joss paper clothes, cars, computers, houses, etc. Many modern jurisdictions have had to impose restrictions on how big joss paper offerings can be.) Nobody knows exactly how the practice started. It had been common in China as in many other places to bury proxy money with the dead -- i.e., replicas of money; that may be the origin of the idea. It was long thought that the practice burning imitation money grew up among the poor, who could not afford the real thing, but as historical evidence has grown, it is clear that the practice has been common among the wealthy for as long as it existed. Very likely it began among the very wealthy -- who, after all, would have had the means to order large quantities of handcrafted paper items solely to burn them -- and in the common pattern we find all the world over, the merchant class and eventually the poor copied the practice of the very wealthy as best they could. It's long been considered bad luck to destroy actual money, so it may be that people started doing it so that they could have fancy offerings that would not tempt fate. Or it may be an adaptation of a Buddhist practice imported from Persia or India. In any case, its popularity became almost universal among Buddhists and Taoists in China and Chinese-influenced cultures, and there are many temples and shrines throughout the area that are able to maintain themselves almost entirely on specialized joss paper sales.
The paper is used as a sort of incense, either in the veneration of ancestors or the worship of Taoist deities; the 'joss' in 'joss paper' indicates this function. As part of the ritual, the one offering the sacrificial money folds it and then burns it, usually at the end of another ritual. Popular accounts seem to assume that people take offering (say) a wad of imitation bills to the fire 'spiritualizes' it so that the spirits can use it in the afterlife or spirit world, but in practice I'm not sure most people see it as more than a gesture expressive of their good will and devotion, and you can also offer it in other ways, like burying it.
In any case, in A Dream of Red Mansions, the practice is portrayed as very widespread and somewhat vulgar. One of the main characters, Baoyu, criticizes it as a late practice (by which he seems to mean merely that it is later than traditional Confucian practices, since the actual use of joss paper may go back to the third century, and in legend it was one of the things invented by Cai Lun, the first inventor of a reliable papermaking process in the first or second century) and contrasts it with the superior Confucian practice of using ordinary incense in traditional rites while acting with the virtue of sincerity.