Why won't the candle core burn out?

Let's popularize the basic knowledge first: paraffin itself can burn, but its burning point is higher than its melting point (strictly speaking, paraffin is amorphous and has no melting point), so it can only burn after providing a lot of heat to melt the wax; For the flame, due to the different amount of oxygen received by different parts, it can be divided into external flame, internal flame and flame center. The outer flame burns the most violently, and the flame center is the worst; The line in the middle of the candle is called wick, which plays the role of absorbing liquid wax oil. Without a wick, the wick melts paraffin slowly, and the melted paraffin will hinder the contact between flame and oxygen, making combustion very difficult. In the case of candle wick, part of external flame and internal flame can also help to melt solid paraffin. More importantly, the wick absorbs paraffin oil, which is heated and melted by the fire above, and then vaporized and burned, which not only prevents paraffin oil from blocking oxygen, but also increases the oxygen absorption area.