The page he opened on was under the heading of Anatomy, and the first passage that drew his eyes was on the valves of the heart. He was not much acquainted with valves of any sort, but he knew that valvae were folding doors, and through this crevice came a sudden light startling him with his first vivid notion of finely adjusted mechanism in the human frame. A liberal education had of course left him free to read the indecent passages in the school classics, but beyond a general sense of secrecy and obscenity in connection with his internal structure, had left his imagination quite unbiased, so that for anything he knew his brains lay in small bags at his temples, and he had no more thought of representing to himself how his blood circulated than how paper served instead of gold. But the moment of vocation had come, and before he got down from his chair, the world was made new to him by a presentiment of endless processes filling the vast spaces planked out of his sight by that wordy ignorance which he had supposed to be knowledge. From that hour Lydgate felt the growth of an intellectual passion."
George Eliot (pen name of Mary Anne Evans), Middlemarch, 1874.