A dish of food will fill one stomach, but the next in line is still hungry.

Even a furnace demands more fuel as freezing souls gather to absorb its heat.

But a light that guides one person will guide a hundred.

Be that light.

Shabbat 122a, cited by the Rebbe on many occasions as a lesson in life (see also Shulchan Aruch, Orach Chaim §276).