I wonder how and why they managed to arrive at
Imladris when they did. Was it the
Valar? Perhaps. Perhaps
Lorien sent the dream. Maybe it was
Galadriel? But I guess 'luck' or 'chance' may have played a part-or things beyond the control of the Valar.
Sauron sending the messenger three times to
Dain,
Gollum escaping (Sauron's doing), the dream sent to
Boromir which came from the West, Butterbur forgetting to send the letter,
Merry and
Pippin starting the conspiracy,
Saruman turning
evil and keeping
Gandalf hostage.....several of these fit in with the description of evil, that it will always lead to good or a greater good, several of these are products of accidents of the decisions of individuals who the Valar may not have had any power over-one of these, the dream vision sent to Boromir and
Faramir may have been sent by the Valar, but again it was the upto Boromir and Faramir whether the vision should be heeded, and upto the council and
Denethor who to send and how.