It was our Lord who coined this great name for His disciples. Paul's use of it is probably a reminiscence of the Master's, and so is a hint of the existence of the same teachings as we now find in the existing Gospels, long before their day. Jesus Christ said, 'Believe in the light, that ye may be the children of light'; and Paul gives substantially the same account of the way by which a man becomes a Son of the Light when he says, in the words preceding my text, 'Ye were sometimes darkness, but now are ye light in the Lord.'

Union with Him makes light, just as the bit of carbon will glow as long as it is in contact with the electric force, and subsides again into darkness when that is switched off. To be in Christ is to be a child of light, and to believe in Christ is to be in Him.

But the intense moral earnestness of our Apostle is indicated by the fact that on both occasions in which he uses this designation he does so, not for the purpose of heightening the sense of the honour and prerogative attached to it, but for the sake of deducing from it plain and stringent moral duties, and heightening the sense of obligation to holy living.

'Walk as children of light.' Be true to your truest, deepest self. Manifest what you are. Let the sweet, sacred secrets of inward communion come out in the trivialities of ordinary conduct; make of your every thought a deed, and see to it that every deed be vitalised and purified by its contact with the great truths and thoughts that lie in this name. These are various ways of putting this one all-sufficient directory of conduct.

Now, in the context, the Apostle expands this concentrated exhortation in three or four different directions, and perhaps we may best set forth its meaning if we shape our remarks by these, I venture to cast them, for the sake of emphasis, into a hortatory form.

I. Aim at an all-round productiveness of the natural fruits of the light.

The true reading is, 'Walk as children of light, for the fruit of the light' (not spirit, as the Authorised Version reads it) 'is in all goodness and righteousness and truth.' Now, it is obvious that the alteration of 'light' instead of 'spirit' brings the words into connection with the preceding and the following. The reference to the 'fruits of the spirit' would be entirely irrelevant in this place; a reference to the 'fruit of the light,' as being every form of goodness and righteousness and truth, is altogether in place.

There is, then, a natural tendency in the light to blossom out into all forms and types of goodness. 'Fruit' suggests the idea of natural, silent, spontaneous, effortless growth. And, although that is by no means a sufficient account of the process by which bad men become good men, it is an inseparable element, in all true moral renovation, that it be the natural outcome and manifestation of an inward principle; otherwise it is mere hypocritical adornment, or superficial appearance. If we are to do good we must first of all be good. If from us there are to come righteousness and truth, and all other graces of character, there must, first of all, be the radical change which is involved in passing from separateness in the darkness to union with Jesus Christ in the light. The Apostle's theory of moral renovation is that you must begin with the implantation in the spirit of the source of all moral goodness—viz. Jesus Christ—brought into the heart by the uniting power of humble faith. And then there will be lodged in our being a vital power, of which the natural outcome will be all manner of fair and pure things. Effort is needed, as I shall have to say; but prior to effort there must be union with Jesus Christ.

This wide, general commandment of our text is sufficiently definite, thinks Paul; for if the light be in you it will naturally effloresce into all forms of beauty. Light is the condition of fruitfulness. Everywhere the vital germ is only acted upon by the light. No sunshine, no flowers; darkness produces thin, etiolated, whitened, and feeble shoots at the best. Let the light blaze in, and the blanched feebleness becomes vigorous and unfolds itself. How much more will light be the condition of fruitfulness when the very light itself is the seed from which all fruit is developed.

But, still further, mark how there must be an all-round completeness in order that we shall fairly set forth the glory and power of the light of which our faith makes us children and partakers. The fruit 'is in all goodness and righteousness and truth.' These three aspects—the good, the right, the true—may not be a scientific, ethical classification, but they give a sufficiently plain and practical distinction. Goodness, in which the prevailing idea is beneficence and the kindlier virtues; righteousness, which refers to the sterner graces of justice; truth, in which the prevalent idea is conformity in action with facts and the conditions of man's life and entire sincerity—these three do cover, with sufficient completeness, the whole ground of possible human excellence. But the Apostle widens them still further by that little word all.

We all tend to cultivate those virtues which are in accordance with our natural dispositions, or are made most easy to us by our circumstances. And there is nothing in which we more need to seek comprehensiveness than in the effort to educate ourselves into, and to educe from ourselves, kinds of goodness and forms of excellence which are not naturally in accordance with our dispositions, or facilitated by our circumstances. The tree planted in the shrubbery will grow all lopsided; the bushes on the edge of the cliff will be shorn away on the windward side by the teeth of the south-western gale, and will lean over northwards, on the side of least resistance. And so we all are apt to content ourselves with doing the good things that are easiest for us, or that fit into our temperament and character. Jesus Christ would have us to be all-round men, and would that we should seek to aim after and possess the kinds of excellence that are least cognate to our characters. Are you strong, and do you pride yourself upon your firmness? Cultivate gentleness. Are you amiable, and pride yourself, perhaps, upon your sympathetic tenderness? Try to get a little iron and quinine into your constitution. Seek to be the man that you are least likely to be, and aim at a comprehensive development of 'all righteousness and goodness and truth.'

Further, remember that this all-round completeness is not attained as the result of an effortless growth. True, these things are the fruits of the light, but also true, they are the prizes of struggle and the trophies of warfare. No man will ever attain to the comprehensive moral excellence which it is in his own power to win; no Christian will ever be as all-round a good man as he has the opportunities of being, unless he makes it his business, day by day, to aim after the conscious increase of gifts that he possesses, and the conscious appropriation and possession of those of which he is still lacking. 'Nothing of itself will come,' or very little. True, the light will shine out in variously tinted ray if it be in a man, as surely as from the seed come the blade and the ear and the full corn in the ear, but you will not have nor keep the light which thus will unfold itself unless you put forth appropriate effort. Christ comes into our hearts, but we have to bring Him there. Christ dwells in our hearts, but we have to work into our nature, and work out in action, the gifts that He bestows. They will advance but little in the divine life who trust to the natural unfolding of the supernatural life within them, and do not help its unfolding by their own resolute activity. 'Walk as children of the light.' There is your duty, for 'the fruit of the light is all righteousness.' One might have supposed that the commandments would be, 'Be passive as children of the light, for the light will grow.' But the Apostle binds together, as always, the two things, the divine working and the human effort at reception, retention, and application of that divine work, just as he does in the great classical passage, 'Work out your own salvation, for it is God that worketh in you.'

II. Secondly, the general exhortation of my text widens out itself into this—test all things by Christ's approval of them.

'Proving what is well pleasing unto the Lord.' That, according to the natural construction of the Greek, is the main way by which the Apostle conceives that his general commandment of 'walking as children of the light' is to be carried out. You do it if, step by step, and moment by moment, and to every action of life, you apply this standard—Does Christ like it? Does it please Him? When that test is rigidly applied, then, and only then, will you walk as becomes the children of the light.

So, then, there is a standard—not what men approve, not what my conscience, partially illuminated, may say is permissible, not what is recognised as allowable by the common maxims of the world round about us, but Christ's approval. How different the hard, stern, and often unwelcome prescriptions of law and rigidity of some standards of right become when they are changed into that which pleases the Divine Lord and Lover! Surely it is something blessed that the hard, cold, and to such a large extent powerless conceptions of duty or obligation shall be changed into pleasing Jesus Christ; and that so our hearts shall be enlisted in the service of our consciences, and love shall be glad to do the Beloved's will. There are many ways by which the burden of life's obligations is lightened to the Christian. I do not know that any of them is more precious than the fact that law is changed into His will, and that we seek to do what is right because it pleases the Master. There is the standard.

It will be easy for us to come to the right appreciation of individual actions when we are living in the light. Union with Jesus Christ will make us quick to discern His will. We have a conscience;—well, that needs educating and enlightening, and very often correcting. We have the Word of God;—well, that needs explanation, and needs to be brought close to our hearts. If we have Christ dwelling in us, in the measure in which we are in sympathy with Him, we shall be gifted with clear eyes, not indeed to discern the expedient—that belongs to another region altogether—but we shall be gifted with very clear eyes to discern right from wrong, and there will be an instinctive recoil from the evil, and an instinctive attachment of ourselves to the good. If we are in the Lord we shall easily be able to prove what is acceptable and well-pleasing to Him.

We shall never walk as the children of the light, unless we have the habit of referring everything, trifles and great things, to His arbitrament, and seeking in them all to do what is pleasing in His sight. The smallest deed may be brought under the operation of the largest principles. Gravitation influences the microscopic grain of sand as well as planets and sun. There is nothing so small but you can bring it into this category—it either pleases or displeases Jesus Christ. And the faults into which Christian men fall and in which they continue are very largely owing to their carelessness in applying this standard to the small things of their daily lives. The sleepy Custom House officers let the contraband article in because it seems to be of small bulk. There are old stories about how strong castles were taken by armed men hidden in an innocent-looking cart of forage. Do you keep up a rigid inspection at the frontier, and see to it that everything vindicates its right to enter because it is pleasing to Jesus Christ.

III. Thirdly, we have here another expansion of the general command, and that is—keep well separate from the darkness.

Have no fellowship with the unfruitful works of darkness, but rather reprove them.' Now, your time will not allow me to dwell, as I had hoped to do, upon the considerations to be suggested here. The very briefest possible mention of them is all that I can afford.

'The unfruitful works of darkness';—well, then, the darkness has its works, but though they be works they are not worth calling fruit. That is to say, nothing except the conduct which flows from union with Jesus Christ so corresponds to the man's nature and relations, or has any such permanence about it as to entitle it to be called fruit. Other acts may be 'works' but Paul will not dishonour the great word 'fruit' by applying it to such rubbish as these, and so he brands them as 'unfruitful works of darkness.'

Keep well clear of them, says the Apostle. He is not talking here about the relations between Christians and others, but about the relations between Christian men and the works of darkness. Only, of course, in order to avoid fellowship with the works you will sometimes have to keep yourselves well separate from their doers. Much association with such men is forced upon us by circumstances, and much is the imperative duty of Christian beneficence and charity. But I venture to express the strong and growing conviction that there are few exhortations that the secularised Church of this generation needs more than this commandment of my text: 'Have no fellowship with the unfruitful works of darkness' 'What communion hath light with darkness?' Ah! we see plenty of it, unnatural as it is, in the so-called Church of to-day. 'What concord hath Christ with Belial? What part hath he that believeth with an infidel? Come ye out from among them, and be ye separate.'

And, brethren, remember, a part of the separation is that your light shall be a constant condemnation of the darkness. 'But rather reprove them,' says my text; that is a work that devolves upon all Christians. It is to be done, no doubt, by the silent condemnation of evil which ever comes from the quiet doing of good. As an old preacher has it, 'The presence of a saint hinders the devil of elbow-room for doing his tricks.' The old legend told us that the fire-darting Apollo shot his radiant arrows against the pythons and 'dragons of the slime.' The sons of light have the same office—by their light of life to make the darkness aware of itself, and ashamed of itself; and to change it into light.

But silent reproving is not all our duty. The Christian Church has wofully fallen beneath its duty, not only in regard to its complicity with the social crimes of each generation, but in regard to its cowardly silence towards them; especially when they flaunt and boast themselves in high places. What has the Church said worthy of itself in regard to war? What has the Church said worthy of itself in regard to impurity? What has the Church said worthy of itself in regard to drunkenness? What has the Church said worthy of itself in regard to the social vices that are honeycombing society and this city to-day? If you are the sons of light, walk as the sons of light, and have 'no fellowship with the unfruitful works of darkness'; but set the trumpet to your lips, and 'declare unto My people their transgressions, and to the house of Israel their sin.'