Let us now turn to the human side of salvation, and trace the upward path of the Christian life as presented to us in this Gospel. First, then, we have the doctrine of the new birth: "Except a man be born anew (or, from above), he cannot see the kingdom of God." This is further explained as a being born "of water and of the Spirit"--words which are probably meant to remind us of the birth of the world-order out of chaos as described in Genesis, and also to suggest the two ideas of purification and life. (Baptism, as a symbol of purification, was, of course, already familiar to those who first heard the words.) Then we have a doctrine of _faith_ which is deeper than that of the Synoptists. The very expression [Greek: pisteuein eis], "to believe _on_," common in St. John and rare elsewhere, shows that the word is taking a new meaning. Faith, in St. John, is no longer regarded chiefly as a condition of supernatural favours; or, rather, the mountains which it can remove are no material obstructions. It is an act of the whole personality, a self-dedication to Christ. It must precede knowledge: "If any man willeth to do His will, he shall know of the teaching," is the promise. It is the "_credo ut intelligam_" of later theology. The objection has been raised that St. John's teaching about faith moves in a vicious circle. His appeal is to the inward witness; and those who cannot hear this inward witness are informed that they must first believe, which is just what they can find no reason for doing. But this criticism misses altogether the drift of St. John's teaching. Faith, for him, is not the acceptance of a proposition upon evidence; still less is it the acceptance of a proposition in the teeth of evidence. It is, in the first instance, the resolution "to stand or fall by the noblest hypothesis"; that is (may we not say?), to follow Christ wherever He may lead us. Faith begins with an experiment, and ends with an experience.[65] "He that believeth in Him hath the witness in himself"; that is the verification which follows the venture. That even the power to make the experiment is given from above; and that the experience is not merely subjective, but an universal law which has had its supreme vindication in history,--these are two facts which we learn afterwards. The converse process, which begins with a critical examination of documents, cannot establish what we really want to know, however strong the evidence may be. In this sense, and in this only, are Tennyson's words true, that "nothing worthy proving can be proven, nor yet disproven."