While this is true and plain, it is no less true that the impossible is incredible, and therefore cannot be an object of faith. Christians concede to reason the judicium contradictionis, that is, the prerogative of deciding whether a thing is possible or impossible. If it is seen to be impossible, no authority, and no amount or kind of evidence can impose the obligation to receive it as true. Whether, however, a thing be possible or not, is not to be arbitrarily determined.