Rocks, Pebbles, Sand

Biological Parallel

Bears entering hibernation pack calories in priority sequence: first, massive fat reserves (rocks)—the only resource that matters for 5-month survival. Then, glycogen and protein stores (pebbles). Finally, micronutrients (sand). Reverse the sequence and they die—no amount of sand fills the space of missing rocks. The metaphor isn't motivational—it's resource loading order. Big constraints must be satisfied first, or small tasks fill time without building capacity.