The Rebbe explains the meaning behind the Baal HaHilula’s description of his students as “candles to illuminate,” drawing parallels between a physical flame and the soul’s mission—using Torah and mitzvot to illuminate oneself and the world, thereby advancing the purpose of creation and hastening the coming of Mashiach.
https://www.torahrecordings.com/rebbe/004_igros_kodesh/adar_beis/959