When do we receive truth? Many such questions are best answered by the asking of another question. Perhaps something like, when does soil receive rain?
When does soil receive seeds? When does truth start to grow? Here, this seems to happen most often when the 'ground' has been plowed, when it is softened, when it is open. Otherwise, rain (and truth) seems to just run off the surface to the side.
So how do we become receptive to truth? We can do some of the tilling ourselves, often with life's help, by how we choose to live. Or, God can till us (also, often with life's help)...sometimes simply from the consequences of our own hardness or lack of receptivity.
What makes us receptive? Or, perhaps another way towards the question, what makes us hard?
