Why do Chinese people talk about giving things in pairs.

In the consciousness of the Chinese people into pairs is a very auspicious and festive saying, from the ancient road to the present day our consciousness tells us into a pair of things is good, like dependence, single is lonely is lonely, we have only heard of the lone soul wild ghosts, but have not heard of the double ghosts, in the absence of emancipation before the rise of the people to find a companion for him after his death, is the meaning of this! I think this is the traditional Chinese consciousness left behind by osmosis.