§ Of the Coming of the Elves and the Captivity of Melkor The Silmarillion

Thus it was that the Valar found at last, as it were by chance, those whom they had so long awaited. And Oromë looking upon the Elves was filled with wonder, as though they were beings sudden and marvellous and unforeseen; for so it shall ever be with the Valar. From without the World, though all things may be forethought in music or foreshown in vision from afar, to those who enter verily into Eä each in its time shall be met at unawares as something new and unforetold.