Just as we welcome Shabbat with kiddush wine and the lighting of candles, so too we take leave of Shabbat with wine and light, as we ready ourselves to reenter the work week. The Greek myth of Prometheus, who was punished by the Gods for stealing their fire and sharing it with man is turned on its head with the Jewish weltanschauung. Judaism celebrates the creativity and productivity of man, as symbolized by fire, and considers this creativity as a blessing from God, Who sees humankind as His partners in Creation, helping to perfect His/our world.
The third ritual element of havdalah is the blessing over the besamim/spices. The sense of smell is considered especially holy, as it is etherial, lacking any materiality. We use the spices to comfort our neshamas, as we sadly witness our extra Sabbath soul (neshama yeterah) take leave for another week.