Faith alone is absolute certainty—it alone has an absolute motive for believing. I have an adequate motive to determine my assent practically, as my mind must do one or another if indifference is impossible—I may have the anxiety of doubt. I may have sufficient motive to believe, but never absolute. I do not call mathematics certainty, not because I doubt, but because they are not the subject of doubt. I may be ignorant, or I know that diverse forms are equal in quantity. I do not say “I doubt”—I am certain; but I am ignorant—“I know."