How do I explain breastfeeding my newborn to my older child?

i would breastfeed in a very natural way, and let my older one watch whenever she came in the room or wanted to be around me. i told her that when baby cries, the food is inside mamma's body and only mamma can give baby the food. so, almost by instinct, each time the baby cried, my older one would come running and tell me mamma it is time for baby's milk, give her food :)