Three miraculous gifts sustained Israel in the wilderness, and each one was tied to a specific leader. Rabbi Yehoshua teaches that when Miriam died, the well that had followed the Israelites through the desert was removed. It returned — but only in the merit of Moses and Aaron, who were still alive.
When Aaron died, the pillar of cloud that guided and protected Israel disappeared. Both the well and the cloud were then restored, sustained by the merit of Moses alone. He carried the spiritual weight of all three gifts on his shoulders.
But when Moses himself died, everything vanished. The well, the cloud, and even the tzirah — the miraculous swarm of hornets that (Exodus 23:28) says God sent ahead of Israel to drive out the Canaanites — all ceased at once. The hornets never crossed the Jordan River into the Promised Land, because their power had operated solely through the merit of Moses.
This teaching links each miracle not to abstract divine generosity but to the personal righteousness of individual human beings. Miriam merited the water. Aaron merited the cloud. Moses merited everything else. When the righteous die, the gifts they sustained die with them. The Mekhilta is making a profound claim: the world runs on the merit of specific people. Remove them, and the miracles they anchored disappear.