In Theravadha Buddhism, Bhikkus can't live in isolation as in Mahayaana or Xianity. Bhikkus live in interdependent relationship with lay. That is to say: a Bhikkhu is not an entity in isolation. He is a Bhikkhu only in relation to lay people: and vice-versa. In isolation, each of these types function according to it's own ways, i.e. of practice.
It is only when they come together that they can learn their respective roles &/or train each other, interactively & interdependently. So much so, that for a Bhikkhu to travel alone, with/to lay folk, his personal practice must be very solid. For this interaction/interdependence is at the very centre of the Middle Way: making meditators of both Bhikkhus & lay folk.