If the salt would only keep its savour--there is the weak point. We know and feel it after the experience of all these centuries. And did not our omniscient Lord lay His finger on it at the very outset? He needed not that any one should tell Him what was in man. He knew that there was that in His truth which would be genuinely and efficiently conservative; but He knew equally well that there was that in man which would to a large extent neutralise that conservative power, that the salt would be in constant danger of losing its savour. Hence, after the encouraging words "Ye are the salt of the earth," He gives an earnest warning which necessarily moderates the too sanguine anticipations that would otherwise have been excited.
Alas! with what sad certainty has history proved the need of this warning! The salt lost its savour in the churches of the East, or it would never have been cast out and trodden underfoot of the Mohammedan invaders. It lost its savour in the West, or there would have been no papal corruption, growing worse and worse till it seemed as if Western Christendom must in turn be dissolved--a fate which was only averted by the fresh salt of the Reformation revival. In modern times there is ever the same danger, sometimes affecting all the churches, as in the dark days preceding the revival under Whitefield and Wesley, always affecting some of them or some portions of them, as is too apparent on every hand in these days in which we live. There is as much need as ever to lay to heart the solemn warning of the King. It is as pungent as salt itself. "Of what use," He asks, "is tasteless salt? It is fit only to be cast out and trodden under foot of men." Equally useless is the so-called Christian, who has nothing in character or life to distinguish him from the world; who, though he may be honest and truthful and sober, a very respectable citizen of an earthly kingdom, has none of the characteristic marks of the kingdom of heaven, none of the savour of the beatitudes about him. It is only because there are still so many savourless Christians that the value of the Church as a conservative influence on society is so little recognised; and that there are so many critics, not all unintelligent or wilfully unfair, who begin to think it is time that it were cast out and trodden under foot of men.
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"_Ye are the light of the world._" We need not stay to show the liberality of light. Its peculiar characteristic is giving, spending; for this purpose wholly it exists, losing its own life in order to find it again in brightness diffused on all around.
Observe, it is not "Ye carry the light," but "Ye _are_ the light." We are apt to think of light in the abstract--as truth, as doctrine, as something to be believed and held and expounded. We quote the familiar words, "Great is the Truth, and it shall prevail," and we imagine they are true. They are true indeed, in the long run, but not as often understood, certainly not in the region of the moral and spiritual. Of course truth in the abstract, especially moral and spiritual truth, ought to prevail; but it never does when men's interests lie, or seem to lie, in the contrary direction. Such truth, to be mighty, must be vitalised; it must glow in human hearts, burn on human tongues, shine in human lives. The King of truth knew this well; and hence He placed the hope of the future, the hope of dispelling the world's darkness, not in abstract truth, but in truth incarnate in the true disciple: "_Ye_ are the light of the world."
In the strictest and highest sense, of course, Christ Himself is the Light of the world. This is beautifully set forth in discourses reported by another Evangelist (John viii. 12, ix. 5); and, indeed, it has been already taught by implication in the Evangel before us, where, as we have seen, the opening of Christ's ministry is likened to sunrise in the land of Zebulon and Naphtali (chap. iv. 16). But the personal Christ cannot remain upon the earth. Only for a few years can He be in this way the Light of the world, as He expressly says in one of the passages above referred to (John ix. 5); and He is speaking now not for the next few years but for the coming centuries, during which He must be represented by His faithful disciples, appointed to be His witnesses (Acts i. 8) to the ends of the earth; so at once He puts the responsibility on them, and says, "Ye are the light of the world."