Māna: Conceit
Māna is the habit of measuring yourself against others. Forty years with no field to plow and no barn to fill leaves that measuring nothing to stand on, since a man with an empty bowl cannot rank himself by his harvest. Being brought low works here as instruction: it strips out the quiet "I fed myself" that a full granary lets a person believe.
Bhojane mattaññutā: Knowing the right amount in food
Mattaññutā is knowing when enough is enough at the table. Hunger permitted first, then a portion that appears each morning and spoils by evening, holds a person at exactly the measure of a single day. Whoever gathered much had nothing left over, and that is what a right amount looks like when no one is able to cheat it.
Piṇḍapāta: Almsfood
Piṇḍapāta is food received into a bowl from someone else's hand. Manna fits that exactly: flakes on the ground nobody planted, "which you didn't know, neither did your fathers know," so no family recipe or inherited skill could take the credit. A monk on his morning round eats whatever gets dropped in, and the not-choosing is half of what trains him.
Āhāra: Nutriment
Āhāra counts four foods a life runs on: what you chew, sense contact, intention, and consciousness. Bread is the first of these and only the first, so being fed and still empty is an ordinary condition, not a riddle. The wilderness years test precisely that, putting a people in a place where a full stomach is available and finding out whether it is the whole of living.
Dhammacariyā: Living by the teaching
Dhammacariyā is conducting your life along the teaching. Every word out of the mouth becomes what a person lives on, in the same plain sense that food is what a person lives on, and the words arrive daily the way the flakes did. The Dhamma protects whoever walks in it, and that protection works on manna's terms: gather today, then go out and gather again tomorrow.