The Renaissance painter Raphael's The Transfiguration, done between 1516 and 1520 and now hanging in a museum in Vatican City, is a marvel of color, form, and spiritual sensitivity.  One stands before it in awe.  The way that Raphael inserts an episode from the gospels in the bottom right of the painting heightens its impact, for it shows, more than other paintings of this event, how powerful a happening the Transfiguration was, that is, the irruption of heaven and the supernatural into the material and finite earth.
    

     For those who do not know the story, the gospels tell us of a day when Jesus and the apostles Peter and John hiked to the top of a mountain where, to the apostles' surprise, they saw the prophets Moses and Elijah conversing with Jesus in what appeared to be a glorified state.  In addition, they heard God speaking to them.  In every way, it was, it seemed, a vision of heaven on earth (for more, read Matthew 17, Mark 9, and Luke 9).
     You're free to doubt the veracity or authenticity of this story, of course, but I share it to make this point.  Although when we look at our material world we may find it relatively easy to ignore the possibility of an invisible and supernatural realm beyond it, it's not as easy to ignore it if this present world really is all that is.  Unless billions and billions of people are severely delusional, we ought to at least consider the possibility that their religious and spiritual experiences, questings, and longings might indeed have some basis in reality.
     We may never see what the apostles saw, but we can see that what is physical and natural lives on the edge of what it is and is not, and that the irruption of the invisible into the visible does not undermine either one.  Rather, it verifies the reality of both.