Frederick Buechner puts it so beautifully.

When Jesus comes along saying the greatest command of all is to love God and to love our neighbor, he...is asking us to pay attention. If we are to love God, we must first stop, look, and listen for him in what is happening around us and inside us. If we are to love our neighbors, before doing anything else we must see our neighbors. With our imagination as well as our eyes, that is to say like artists, we must see not just their faces but the life behind and within their faces. Here it is love that is the frame we see them in."