§ Of the Beginning of Days The Silmarillion

But Manwë Súlimo, highest and holiest of the Valar, sat upon the borders of Aman, forsaking not in his thought the Outer Lands. For his throne was set in majesty upon the pinnacle of Taniquetil, the highest of the mountains of the world, standing upon the margin of the sea. Spirits in the shape of hawks and eagles flew ever to and from his halls; and their eyes could see to the depths of the seas, and pierce the hidden caverns beneath the world. Thus they brought word to him of well nigh all that passed in Arda; yet some things were hidden even from the eyes of Manwë and the servants of Manwë, for where Melkor sat in his dark thought impenetrable shadows lay.