Why are strangers who plead for help called “beggars”?

The name of a twelfth-century monk, Lambert de Begue, whose fol-
lowers wandered the French countryside depending on handouts, gave
us the verb to beg. When in 555 AD the Roman general Belisarius was
stripped of his rank and wealth, he became one of history’s most
notable beggars, and his frequent cry, “Don’t kick a man when he’s
down,” gave us a maxim for all who are on very hard times.