The whole question here as between Paul and his opponents just comes to this; if a field is covered with filth, whether is it better to set to work on it with wheel-barrows and shovels, or to turn a river on it which will bear away all the foulness? The true way to change the fauna and flora of a country is to change the level, and as the height increases they change themselves. If we desire to have the noxious creatures expelled from ourselves, we must not so much labour at their expulsion as see to the elevation of our own personal being and then we shall succeed. That is what Paul says, 'Walk in the Spirit, and ye shall not fulfil the lusts of the flesh.' III. Such a life is not freed from the necessity of struggle. The highest condition, of course, would be that we had only to grow, not to fight. It will come some day that all evil shall drop away, and that to walk in the Spirit will need no effort, but that time has not come yet. So in addition to all that we have been saying in this sermon, we must further say that Paul's exhortation has always to be coupled with the other to fight the good fight. The highest word for our earthly lives is not 'victory' but 'contest.' We shall not walk in the Spirit without many a struggle to keep ourselves within that charmed atmosphere. The promise of our text is not that we shall not feel, but that we shall not fulfil, the desires of the flesh. Now this is very commonplace and threadbare teaching, but it is none the less important, and is especially needful to be strongly emphasised when we have been speaking as we have just been doing. It is a historical fact, illustrated over and over again since Paul wrote, and not without illustration to-day, that there is constant danger of lax morality infecting Christian life under pretence of lofty spirituality. So it must ever be insisted upon that the test of a true walking in the Spirit is that we are thereby fitted to fight against the desires of the flesh. When we have the life of the Spirit within us, it will show itself as Paul has said in another place by the righteousness of the law being fulfilled in us, and by our 'mortifying the deeds of the body.' The gift of the Spirit does not take us out of the ranks of the combatants, but teaches us to fight, and arms us with its own sword for the conflict. There will be abundant opportunities of courage in attacking the sin that doth so easily beset us, and in resisting temptations which come to us by reason of our own imperfect sanctification. But there is all the difference between fighting at our own hand and fighting with the help of God's Spirit, and there is all the difference between fighting with the help of an unseen ally in heaven and fighting with a Spirit within us who helpeth our infirmities and Himself makes us able to contend, and sure, if we keep true to Him, to be more than conquerers through Him that loveth us.