What does the old saying Jia Zi and Yi Chou all like to watch the stove mean?

Jiazi is ugly, and Bing Yin and Ding Mao listen to the sound of gold in the sea. Gold is not refined, but everything is refined in the furnace. Heaven and earth are furnaces, and Yin and Yang are charcoal. This is common sense. There are three strange examples in the other eight characters, and those who see them are expensive. From this academic point of view, of course, there are many specific conditions for seeing a fire in the furnace.