Marcia asks whether we can understand inquiry as melting substance back into light. This is very well put.
The same holds for darkeness. What it suggests is that we find light by turning toward darkness and substance and then asking (inquiring) what is missing. A German philosopher once wrote, “In the places everyone looks, there is nothing to see but darkness.” This is helpful, but it seems to me that what matters is not where one looks, but how one looks. If we look expecting to find substance, we find darkness. If we look in a way that invites light, the possibility is there for something quite different.
Peter, you feel fear at not finding your heart. But perhaps the heart is not ‘my heart’, but the heart of experience. The barriers dividing ‘me’ and ‘world’ are barriers that fall as we slip away (see my other post today).
 Michael, I think we will all recognize the dynamic you describe: arriving at a place that is so dark that we cannot continue to accept it. As you wrote, perhaps we don’t have to accept the reality of that dynamic (first the deepest darkness, and out of that the light). Isn’t the point that light itself knows no barriers, knows no darkness? Then how to find ourselves on the side of light instead of darkness? The reading for this week is a wonderful source of guidance.
Jack