1893. These Boyle Lectures begin by showing that which skeptics of all kinds believe, and then what, from their own standpoint, they ought to believe. This accomplished, it is next shown what new necessities and obligations, logical and moral, come from the step already taken; and so forward, point by point, until the Catholic Faith in Christ is reached. Contents: scope of the lectures; classes of agnostics addressed; nature of evidence; preoccupation of worldliness as secularism and positivism; secularistic positivism as critical; concerning the supernatural; supernatural in imitation; supernatural in evolution; certainty as faith in truth and right; certainty as scientific; certainty as religious; certainty as Christian.