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

Through long ages the Valar dwelt in bliss in the light of the Trees beyond. The Mountains of Aman, but all Middle-earth lay in a twilight under the stars. While the Lamps had shone, growth began there which now was checked, because all was again dark. But already the oldest living things had arisen: in the seas the great weeds, and on earth the shadow of great trees; and in the valleys of the night-clad hills there were dark creatures old and strong. To those lands and forests the Valar seldom came, save only Yavanna and Oromë; and Yavanna would walk there in the shadows, grieving because the growth and promise of the Spring of Arda was stayed. And she set a sleep upon many things that had arisen in the Spring, so that they should not age, but should wait for a time of awakening that yet should be.