...when the apostle Paul comes forward to proclaim the will of God, he says it is not by the crushing of the body, but by the sanctification of the body: “I pray God your whole spirit and soul and body be preserved blameless unto the coming of our Lord Jesus Christ.” In this my Christian brethren, there is one of the deepest of all truths. Does a man feel himself the slave and the victim of his lower passions? Let not that man hope to subdue them merely by struggling against them. Let him not by fasting, by austerity, by any earthly rule that he can conceive, expect to subdue the flesh. The more he thinks of his vile and lower feelings, the more will they be brought into distinctness, and therefore into power; the more hopelessly will he become their victim. The only way in which a man can subdue the flesh, is not by the extinction of those feelings, but by the elevation of their character. Let there be added to that character, sublimity of aim, purity of affection; let there be given grandeur, spiritual nobleness; and then, just as the strengthening of the whole constitution of the body makes any particular and local affection disappear, so by degrees, by the raising of the character, do these lower affections become, not extinguished or destroyed by excision, but ennobled by a new and loftier spirit breathed through them. This is the account given by the apostle. He speaks of the conflict between the flesh and the spirit. And his remedy is to give vigour to the higher, rather than to struggle with the lower. “This I say then, Walk in the spirit, and ye shall not fulfil the lust of the flesh.”
...We hear of man's invention, of man's increase of knowledge; and it would seem in all this, as if man were necessarily becoming better. Brethren, it always must be the case in that state in which God is looked upon as the Supreme Being merely, where the intellect of man is supposed to be the chief thing—that which makes him most kindred to his Maker. The doctrine of Christianity is this—that unity of all this discord must be made. Man is to be made one with God, not by soaring intellect, but by lowly love. It is the Spirit which guides him to all truth; not merely by rendering more acute the reasoning powers, but by convincing of sin, by humbling the man. It is the graces of the Spirit which harmonize the man, and make him one; and that is the end, and aim, and object of all the Gospel: the entireness of sanctification to produce a perfectly developed man. Most of us in this world are monsters, with some part of our being bearing the development of a giant, and others showing the proportions of a dwarf: a feeble, dwarfish will—mighty, full-blown passions; and therefore it is that there is to be visible through the Trinity in us, a noble manifold unity; and when the triune power of God shall so have done its work on the entireness of our Humanity, that the body, soul, and spirit have been sanctified, then shall there be exhibited, and only then, a perfect affection in man to his Maker, and body, soul, and spirit shall exhibit a Trinity in unity.
Frederick William Robertson. Sermons Preached at Brighton / Third Series Chapter 4.