The Previous Rebbe related: As a young child I debated whether angels knew the solutions to mathematical equations. After all, they know everything; perhaps they knew this too? I then asked my father, the Rebbe Rashab. My saintly father clarified it for me and went on to say that one thing is certain: The angel Michoel makes an accurate reckoning of all the chapters of Tehillim people recite, and with it he fashions a beautiful chandelier which serves to illuminate the heavenly realms as well as this world for the person and for all his future generations.

Although I was still young, my father would often ask me, "What's doing with the chandelier?"

Sefer HaSichos 5709, p. 336