It is believed, also, by the disciples of Butler, that there is a real strength possessed by what are called the "active powers" of the mind. "This distinction," says Dr. Chalmers, "made by the sagacious Butler between the power of a principle and its authority, enables us in the midst of all the actual anomalies and disorders of our state, to form a precise estimate of the place which conscience naturally and rightly holds in man's constitution. The desire of acting virtuously, which is a desire consequent on our sense of right and wrong, may not be of _equal strength_ with the desire of some criminal indulgence, and so, practically, the evil may predominate over the good. And thus it is that the system of the inner man, from _the weakness_ of that which claims to be the ascendant principle of our nature, may be thrown into a state of turbulence and disorder."--Nat. The. p. 313. Such was the idea of Butler himself. He frequently speaks of the supremacy of conscience, in terms such as the following: "That principle by which we survey, and either approve or disapprove, our heart, temper, and actions, is not only to be considered as what in its turn is to have some influence, which may be said of every passion, of the basest appetite; but likewise as being superior; as from its very nature manifestly claiming superiority over all others; insomuch that you cannot form a notion of this faculty conscience, without taking in judgement, direction, and superintendency. This is a constituent part of the idea, that is of the faculty itself; and to preside and govern, from the very economy and constitution of man, belongs to it. Had it _might_, as it has right; had it _power_, as it has manifest authority; it would absolutely govern the world." This language, it should be observed, is not used in a metaphorical sense; it occurs in the statement of a philosophical theory of human nature. Similar language is frequently to be found in the writings of the most enlightened advocates of free-agency. Thus, says Jouffroy, even while he is contending against the doctrine of necessity: "There are two kinds of _moving powers_ acting upon us; first, the impulses of instinct, or passion; and, secondly, the conceptions of reason. . . . . That these two kinds of moving powers can and do, act efficiently upon our volitions, there can be no doubt," p. 102. If it were necessary, it might be shown, by hundreds of extracts from their writings, that the great advocates of free-agency have held, that the emotions, desires, and passions, do really act on the will, and tend to produce volitions.