If I may not assume that I exist, and in a particular way, that is, with a particular mental constitution, I have nothing to speculate about, and had better let speculation alone. Such as I am, it is my all; this is my essential stand-point, and must be taken for granted; otherwise, thought is but an idle amusement, not worth the trouble. There is no medium between using my faculties, as I have them, and flinging myself upon the external world according to the random impulse of the moment, as spray upon the surface of the waves, and simply forgetting that I am. I am what I am, or I am nothing. I cannot think, reflect, or judge about my being, without starting from the very point which I aim at concluding. My ideas are all assumptions, and I am ever moving in a circle. I cannot avoid being sufficient for myself, for I cannot make myself anything else, and to change me is to destroy me. If I do not use myself, I have no other self to use. My only business is to ascertain what I am, in order to put it to use. It is enough for the proof of the value and authority of any function which I possess, to be able to pronounce that it is natural. What I have to ascertain is the laws under which I live. My first elementary lesson of duty is that of resignation to the laws of my nature, whatever they are; my first disobedience is to be impatient at what I am, and to indulge an ambitious aspiration after what I cannot be, to cherish a distrust of my powers, and to desire to change laws which are identical with myself.