It is the characteristic of certitude that its object is a truth, a truth as such, a proposition as true. There are right and wrong convictions, and certitude is a right conviction; if it is not right with a consciousness of being right, it is not certitude. Now truth cannot change; what is once truth is always truth; and the human mind is made for truth, and so rests in truth, as it cannot rest in falsehood. When then it once becomes possessed of a truth, what is to dispossess it? but this is to be certain; therefore once certitude, always certitude. If certitude in any matter be the termination of all doubt or fear about its truth, and an unconditional conscious adherence to it, it carries with it an inward assurance, strong though implicit, that it shall never fail. Indefectibility almost enters into its very idea, enters into it at least so far as this, that its failure, if of frequent occurrence, would prove that certitude was after all and in fact an impossible act, and that what looked like it was a mere extravagance of the intellect. Truth would still be truth, but the knowledge of it would be beyond us and unattainable. It is of great importance then to show, that, as a general rule, certitude does not fail; that failures of what was taken for certitude are the exception; that the intellect, which is made for truth, can attain truth, and, having attained it, can keep it, can recognize it, and preserve the recognition. This is on the whole reasonable; yet are the stipulations, thus obviously necessary for an act or state of certitude, ever fulfilled? We know what conjecture is, and what opinion, and what assent is, can we point out any specific state or habit of thought, of which the distinguishing mark is unchangeableness? On the contrary, any conviction, false as well as true, may last; and any conviction, true as well as false, may be lost. A conviction in favour of a proposition may be exchanged for a conviction of its contradictory; and each of them may be attended, while they last, by that sense of security and repose, which a true object alone can legitimately impart. No line can be drawn between such real certitudes as have truth for their object, and apparent certitudes. No distinct test can be named, sufficient to discriminate between what may be called the false prophet and the true. What looks like certitude always is exposed to the chance of turning out to be a mistake. If our intimate, deliberate conviction may be counterfeit in the case of one proposition, why not in the case of another? if in the case of one man, why not in the case of a hundred? Is certitude then ever possible without the attendant gift of infallibility? can we know what is right in one case, unless we are secured against error in any? Further, if one man is infallible, why is he different from his brethren? unless indeed he is distinctly marked out for the prerogative. Must not all men be infallible by consequence,