Neighbouring as a Practice of Care

Am I your neighbour simply because we inhabit the same building, perhaps separated only by a wall? Am I your neighbour for the fleeting span of a shared seat on the U-Bahn or the bus? Am I your neighbour because I hold the elevator door — or because I kneel beside you to gather the groceries scattered from a torn paper bag? I suppose what I am trying to say is this: am I your neighbour because of what I do for you? And are you then my neighbour because I do these things for you? Must this relationship be reciprocated? Would we still be neighbours if we paid no attention to one another?