A good deal of Chinese symbolic imagery works by homophony, and the monkey is a standard example: the word for monkey, hou, sounds like the word for a marquis or nobleman, so an image of a monkey on a horse can be read as a wish for immediate promotion to high office. This kind of visual punning is the mechanism behind much of the auspicious imagery on Chinese ceramics, embroidery and New Year prints, and it is quite distinct from the symbolic logic of European emblem traditions. The monkey belongs to the san he triad with the Rat and the Dragon and stands opposite the Tiger. As with the other signs, its almanac character is a popular tradition assembled from several layers, literary, religious and linguistic, rather than a single doctrine.
Homophonic wordplay of the kind described here for the monkey runs throughout the whole system of twelve animals to varying degrees, the bat, not one of the twelve but a frequent companion image in New Year prints, is a particularly well-known example, since fu, bat, is a homophone of fu, blessing, and five bats together represent the Five Blessings; the monkey-on-horseback pun for immediate promotion is one specific and well-attested instance of this broader visual-linguistic tradition rather than an isolated case peculiar to this sign alone.