It "setteth on fire the wheel of nature, and is set on fire by hell." We must be content to leave the precise meaning of the words rendered "the wheel of nature" (τὸν τροχὸν τῆς γενέσεως) undetermined. The general meaning is evident enough, but we cannot be sure what image St. James had in his mind when he wrote the words. The one substantive is obviously a metaphor, and the other is vague in meaning (as the latter occurs i. 23, the two passages should be compared in expounding); but what the exact idea to be conveyed by the combination is, remains a matter for conjecture. And the conjectures are numerous, of which one must suffice. The tongue is a centre from which mischief radiates; that is the main thought. A wheel that has caught fire at the axle is at last wholly consumed, as the fire spreads through the spokes to the circumference. So also in society. Passions kindled by unscrupulous language spread through various channels and classes, till the whole cycle of human life is in flames. Reckless language first of all "defiles the whole" nature of the man who employs it, and then works destruction far and wide through the vast machinery of society. And to this there are no limits; so long as there is material, the fire will continue to burn.
How did the fire begin? How does the tongue, which was created for far other purposes, acquire this deadly propensity? St. James leaves us in no doubt upon that point. It is an inspiration of the evil one. The enemy, who steals away the good seed, and sows weeds among the wheat, turns the immense powers of the tongue to destruction. The old serpent imbues it with his own poison. He imparts to it his own diabolical agency. He is perpetually setting it on fire (present participle) from hell.
The second metaphor by which the malignant propensity of the tongue is illustrated is plain enough. It is an untamable, venomous beast. It combines the ferocity of the tiger and the mockery of the ape with the subtlety and venom of the serpent. It can be checked, can be disciplined, can be taught to do good and useful things; but it can never be tamed, and must never be trusted. If care and watchfulness are laid aside, its evil nature will burst out again, and the results will be calamitous.
There are many other passages in Scripture which contain warnings about sins of the tongue: see especially Proverbs xvi. 27, 28; Ecclus. v. 13, 14, and xxviii. 9-23, from which St. James may have drawn some of his thoughts. But what is peculiar to his statement of the matter is _this_, that _the reckless tongue defiles the whole nature of the man who owns it_. Other writers tell us of the mischief which the foul-mouthed man does to others, and of the punishment which will one day fall upon himself. St. James does not lose sight of that side of the matter, but the special point of his stern warning is the insisting upon the fact that unbridled speech is a _pollution_ to the man that employs it. Every faculty of mind or body with which he has been endowed is contaminated by the subtle poison which is allowed to proceed from his lips. It is a special application of the principle laid down by Christ, which was at first a perplexity even to the Twelve, "The things which proceed out of the man are those that defile the man" (Mark vii. 15, 20, 23). The emphasis with which Christ taught this ought to be noticed. On purpose to insist upon it, "He called to Him the multitude _again_, and said unto them, Hear ye _all_ of you, and _understand_: there is nothing from without the man, that going into him can defile him; but the things which proceed out of the man are those that defile the man." And He repeats this principle a second and a third time to His disciples privately. "Are ye so without understanding also?... That which proceedeth out of the man, that defileth the man.... All these things proceed from within, and defile the man." If even an unspoken thought can defile, when it has not yet proceeded farther than the heart, much greater will be the pollution if the evil thing is allowed to come to the birth by passing the barrier of the lips. This flow of evil from us means nothing less than this, that we have made ourselves a channel through which infernal agencies pass into the world. Is it possible for such a channel to escape defilement?