Round Cotton Wicks

There is a deeper significance to the diya.  The oil in the diya symbolises the dirt in the human mind — such as greed, jealousy, hatred, lust etc — which human beings tend to nurture. The cotton in the diya is symbolic of the atma or the self or the soul. The diya presents light when the oil is burnt by the wick. Hence, lighting of the diyas signifies that one needs to get rid of the selfish and materialistic thoughts. This frees one from all forms of sadness, guiding the path to enlightenment and to connect with the Supreme Being. 

However, the wick also has a very critical role. The purpose of a wick is to deliver fuel (wax) to the flame. Acting like a fuel pump, the wick draws the liquefied wax up into the flame to burn.