"Woe unto the world," said our blessed Lord, "because of occasions of stumbling! For it must needs be that the occasions come; but woe to that man through whom the occasion cometh" (Matt. xviii. 7). Human nature being what it is, it is morally impossible that no one should ever lead another into sin. But that fact does not destroy the responsibility of the individual who leads his fellows into sin. St. Paul takes up the principle thus laid down by Christ and applies it in a particular sphere. He tells his Corinthian converts that "there must be heresies" among them, and that they serve the good purpose of sifting the chaff from the wheat. Wherever the light comes, it provokes opposition; there is at once antagonism between light and darkness. This is as true in the sphere of faith and morals as in that of the material world. Sooner or later, and generally sooner rather than later, truth and innocence are met and opposed by falsehood and sin; and it is falsehood, wilfully maintained in opposition to revealed and generally held truth, that constitutes the essence of heresy. There are many false opinions outside what God has revealed to mankind, outside the scope of the Gospel. However serious these may be, they are not heresies. A man may be fatally at fault in matters of belief; but, unless in some sense he accepts Christianity as true, he is no heretic. As Tertullian says, "In all cases truth precedes its copy; after the reality the likeness follows" (_De Præs. Hær._, xxix). That is, heresy, which is the caricature of Christian truth, must be subsequent to it. It is a distortion of the original truth, which some one has arrogantly chosen as preferable to that of which it is the distortion. Error which has not yet come in contact with revelation, and which has had no opportunity of either submitting to it or rebelling against it, is not heretical. The heretical spirit is seen in that cold critical temper, that self-confident and self-willed attitude, which accepts and rejects opinions on principles of its own, quite independently of the principles which are the guaranteed and historical guides of the Church. But it cannot accept or reject what has never been presented to it; nor, until the Christian faith has to some extent been accepted, can the rejection of the remainder of it be accounted heresy. Heresy is "a disease of Christian knowledge." The disease may have come from without, or may have developed entirely from within; and in the former case the source of the malady may be far older than Christianity itself. But until the noxious elements have entered the Christian organism and claimed a home within the system, it is a misuse of language to term them heretical.