He was always hungry, her Drogon. Hungry and growing fast. Another year, or perhaps two, and he may be large enough to ride. Then I shall have no need of ships to cross the great salt sea.
But that time was not yet come. Rhaegal and Viserion were the size of small dogs, Drogon only a little larger, and any dog would have outweighed them; they were all wings and neck and tail, lighter than they looked. And so Daenerys Targaryen must rely on wood and wind and canvas to bear her home
George R. R. Martin - A Storm of Swords
The woman took a step backward. “You must leave this city soon, Daenerys Targaryen, or you will never be permitted to leave it at all.”
Dany’s wrist still tingled where Quaithe had touched her. “Where would you have me go?” she asked.
“To go north, you must journey south. To reach the west, you must go east. To go forward you must go back, and to touch the light you must pass beneath the shadow.
George R. R. Martin - A Clash of Kings