One night Piazzolla was eating in a greasy restaurant (un bachín) when a little boy (un chiquilin) walked table-to-table selling flowers. Piazzolla and his companions began to wonder what life is like for such a boy, so they followed him through the streets of Buenos Aires. Upon the conclusion of their journey Piazzolla wrote this tune. I played it on Tango for One (shameless self promotion) there is also a fantastic version by violinist Gidon Kremer that is worth a listen.