The `only pretension, of which I am tenacious,' declares William Hazlitt in The Plain Speaker, `is that of being a metaphysician'; yet up till now his metaphysics, and particularly what is here identified as his `power principle', have not been examined in detail. This book identifies the metaphysical Hazlitt within the other and better-known Hazlitt, long acknowledged as a master of `the familiar style' and more recently celebrated for the fierceness and intensity of his political prose. Studying his development of the power principle as a counter to the pleasure principle of the Utilitarians, it examines the revelation of power in his philosophy of discourse, his account of imaginative structure, his theory of genius, and his moral theory, and asserts the tenacity of this principle throughout his work. Disseminated through the range of his writings, Hazlitt's metaphysics becomes a metaphysics of power in more senses than one: it is both argument and example, itself manifesting that force of human intellect that it seeks to explicate.