"The soul of man is a lamp of G-d" (Proverbs 20:27). Just like the flame of the lamp strains upwards, seeking to tear free of the wick and rise heavenward - though this would spell its own demise - so, too, does the G-dly soul in man constantly strive to tear free of the body and the material existence and be nullified within its source in G-d.
Rabbi Schneur Zalman of Liadi
