The decoration of a piece of Chinese art often serves two purposes. Besides simply decorating the surface, the decoration usually presents a veiled auspicious meaning. By having these things bearing auspicious meanings their wishes will come true. Often the decoration represents a four character phrase. Thus many of the decorative motif are rebuses or pictorial puns, that is, groups of seemingly unrelated objects whose names share the same sounds as the auspicious wish.
Most Chinese decorative art are based on its symbolic values. These symbols could be understood and interpreted and only when we do that the true meaning of the objects reveals itself. This is very similar to medieval Dutch art, where every item that occurs in a picture carries a hidden religious meaning, and most religious art still does all over the world. It is also true that the 'hidden' meaning is only hidden to those who do not 'know'. The picture of a white lily in Chiristian art is 'purity' in much the same way as a 'lotus' is, in Buddhistic art. A dog is the symbol of 'trustworthiness' in much the same way as the bamboo is in Chinese art, and so forth.
When the symbolic content is taken into consideration an entire new world opens up and the objects begin to talk to you. Everything seems to be connected to a rich world of ideas, stories, myths and religious and philosophical beliefs. When trying to interpret a certain decoration it is often the case that it is made from a particular point of view; it could be Daoist, Buddhist, Confucian, Traditional, Astronomical, "Feng shui", Mythical, Literary, Historical, and Homonymic, or a little of everything. Many symbols can carry several meanings and which is the intended in a specific case can often only be understood by its context.
There is no limit to how much one needs to know, to understand the full meaning of Chinese symbolism, but to have any meaning or purpose, any symbol must somehow refer to a general and not too elusive meaning. The symbols are also of different kinds.
Literary and historical allusive symbols are those taken from poetry, history or popular stories. This is mostly entire scenes which on porcelain usually seems to have been copied from wood block prints. These illustrations must be recognized to be understood and you should preferably have read the story to get the point. These historical or mythical figures have often done something in a special way, or for a specific purpose, and something or other as thus was understood, and the use of these figures in a decoration are there to remind us about this.
Iconographic, religious or philosophical symbols are related to ideas which must be known, for the symbols to be understood. These symbols must be drawn in a specific way. The Buddhist 'endless knot' or the 'chacra' are special icons and not any knot or wheel will carry the intended meaning. Sometimes even the order in which these icons appear might have an importance for their meaning.
Homonymic symbols are based on the similarities in sound between a specific word and the name of the symbol in question like 'Bat' - fu - where the word 'fu' sounds pretty much like the same word 'fu' meaning 'happiness'. Stylized pictures of bats are thus widely used to symbolize 'happiness'. The use of the number of bats can also refer to a further concept of for example five bats meaning The Five Happinesses, and so on.
Conceptual symbols finally, are those that do not need to be drawn in any specific way to carry their symbolic meaning. A 'vase' is always a receptacle, and thus 'female' from a Daoist point of view. 'Red' is always the color of luck and prosperity. The number 'five' has always its meaning - often 'The Five Directions' - however it is used or drawn. A 'peony' always has its feminine value and a 'pine', 'willow', 'bamboo' or 'deer', etc. carry their meanings in whatever form they are found.
It is this mix symbols, of all sizes and in a happy disregard of proportions and the western notion of perspective, that gives Chinese art its unique flavor.