We pass on now to supernatural signs or _Miracles_ in the strict sense; which we will define as _marvels specially worked by God as signs to confirm a revelation_. This definition has, of course, been chosen so as to suit the miracles recorded in the Bible, and it is really threefold. In the first place, a miracle is described as to its outward _appearance_. It is a marvel--that is to say, a strange and unusual event, which we cannot account for, and which thus attracts attention. Secondly, it is described as to its _cause_. This marvel is said to have been specially worked by God--that is to say, by some action on His part different from His usual action in nature. While, lastly, it is described as to its _purpose_; it is a marvel worked by God as a sign to confirm a revelation. The first of these aspects is expressed in the Old Testament by the word _wonder_, the second by such phrases as God's _mighty hand_ or _outstretched arm_, and the third by the word _sign_; all these terms being often used together. While in the New Testament the words used are _wonders_, _mighty works_, and _signs_, which again exactly correspond to these three aspects of the miracles. And it should be noticed these aspects are not chosen merely to suit the present argument, since other events can and ought to be looked at in the same way, not as mere facts, but also with reference to their alleged cause and purpose. And to show the great importance of this, we will consider an event from modern history; and select the well-known example of the Mont Cenis Tunnel. Suppose, then, that anyone heard of this as a _marvel_ only, the cause and purpose being left out of account. Suppose, that is, he heard that a small straight cavity of uniform size, and several miles long, had been formed under a range of mountains; and that it had begun as two cavities, one from each end, which after years of growth, had exactly met in the middle. He would at once pronounce the event incredible, for the cavity is quite unlike all natural cavities. But now suppose the next point, as to its _cause_, to be introduced. It is said to be something more than a natural cavity, and to be the work of man. All previous difficulties would now vanish, but fresh ones would arise. For numbers of men must have worked together for years to excavate such a cavity, and from what we know of human nature, men will only do this for commercial or profitable ends, and not for boring useless holes through mountains; so the event is still practically incredible.