The Powers, and the One who is above them, really do take an interest in
Middle-earth, whether or not its inhabitants are aware of them. Gandalf is
himself a Maia, but he is confined to Human form (although the White version
has enhanced powers), and I think his ability (as Gandalf the Grey) to hear Eru
or the Valar is quite limited. He "sees through a glass, darkly". So he must
rely on the urgings of his heart, going where the road leads him. By being
willing to travel the road, he lets himself be a conduit for the powers. It
might appear as "chance" to many, but I think that Gandalf knows
better.
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Do we find happiness so often that we should turn it off the box when it happens to sit there?
- A Room With a View