Letting things run there course

[Sween]

What was tolkien trying to get across with his phiolophy of letting things run there course. In lord of the rings he just lets Sam and Frodo get on with it Gandalf refuses to get involved with them he doesnt even make any atempt to find them really.

In the Silmarillion he also has the powers (the Valar) just sit back and watch things unfold. they do have some idea of the futre. Mandos in Morgoths ring says about letting Finwe remarry that history will be better for it ere the end when Earendil comes out of the sea or summet. So they have a good idea of whats going to happen.

Did the Valar know the Two Trees were going to be thrown down? if they have some vision of the futre then they must have some idea of the events inbetween? or do they just know that the world will be allright in the end? I see middle earth history much as a play all pre concived and pre ordained with good guys, bad guys and people who are just unlucky and is there fait in there hands or is there life mearly the fullfilment of there destinty?

Thingol in the end just lets Beren and Luthien marry because he realises that it was ment to be and it was a power beyond him and really is wasnt even to do with Beren and Luthien to be together they were ment to be together thats why Beren came through Melians enchantments etc.

There is also the case of Tuor at the Nirnaeth Arnoediad Hour said to Turgon 'a new star shall arise from us' as of course was the case so in the end allthough he didnt head Tuors messages from Ulmo (whom of all the Valar did try and effect change in Beleriand) he didnt stop. Also by the end of the third age they seemed to reconise theses things quite easily and Elrond came to the conclusion that he had little or no power to stop Arwen and Aragon marring.

So what intrests me is how much did the Valar know and how much did they infact effect change in the world and should they or taken over a bit more and saved a lot of hurt to the world?