The discussion centers on the phenomenon of relighting a candle by igniting the fumes that rise from the wick after it has been blown out. It explains that after extinguishing the flame, ignitable fumes, not smoke, ascend from the wick, allowing for the possibility of relighting. The wick absorbs melted wax, which then vaporizes and burns, necessitating heat to convert the wax into a flammable gas. The ability to reignite the candle is enhanced when a visible string of smoke is present, as it can carry the flammable vapor back to the wick. Overall, this trick demonstrates the fascinating behavior of candle wax and vapor dynamics.