The sentence above appears towards the end of The Hobbit. It is a foreshadowing by Tolkien who devises his main character (and apparently his mouthpiece) Gandalf the Wizard as the chief strategist at the renowned sequel Lord of the Rings. Eventually Gandalf proves that he is the one that the Elvenking puts wishfully. He is Gandalf, the Grey in the beginning and turns “White” in the progress. Yet he is one of the most curious characters in the Lord of the Rings. Here is a compilation consists of bits and pinches of information found in Tolkien’s writings.
Gandalf is one of the chief Istari of Wizards of Middle-earth, also known as Mithrandir, the ‘Grey Wanderer’, friend of all Free Peoples. The Greatest opponent of the Dark Lord in the Third Age, Gandalf passed through fire, earth, water and death – and was afterwards reborn – in fulfillment of the destiny long appointed for him: to be the chief architect of Sauron’s downfall.