In his lengthy discussion of the Decalogue in Institutes of the Christian Religion, Calvin expresses a dual truth; that we are to love all mankind without exception, and that those who are tied more closely to us should benefit from our special loving attention.
I do not deny that the more closely a man is linked to us, the more intimate obligation we have to assist him. It is the common habit of man that the more closely men are bound together by ties of kinship, of aquaintanceship, or of neighbourhood, the more responsibilities for another they share. This does not offend God; for his providence, as it were, leads us to it. But I say: we ought to embrace the whole human race without exception in a single feeling of love … for all should be contemplated in God, not in themselves. (Institutes 2.8.55)
It would be anachronistic to apply the word ‘subsidiarity’ to this quote, but the core of the doctrine is there. Calvin describes it as a work of God’s providence that we are closely tied to those we are tied to. He arranges the world in such a way. And yet subsidiarity does not define the limits of love for neighbour; it is God who defines the limits. And He posits himself as the limit, according to Calvin. It is a love-boundary no-one will ever reach.