The source of this strength is not in ourselves. We are to be “strengthened _with_ [or _by_] _power_,”--by “the power” of God “working in us” (ver. 20), the very same “power, exceeding great,” that raised Jesus our Lord from the dead (i. 19). This superhuman might of God operating in men is always referred to the Holy Spirit: “by power made strong,” he says, “_through the Spirit_.” Nothing is more familiar in Scripture than the conception of the indwelling Spirit of God as the source of moral strength. The special power that belongs to the gospel Christ ascribes altogether to this cause. “Ye shall receive power,” He said to His disciples, “after that the Holy Spirit is come upon you.” Hence is derived the vigour of a strong faith, the valour of the good soldier of Christ Jesus, the courage of the martyrs, the cheerful and indomitable patience of multitudes of obscure sufferers for righteousness’ sake. There is a great truth expressed when we describe a brave and enterprising man as a _man of spirit_. All high and commanding qualities of soul come from this invisible source. They are inspirations. In the human will, with its _vis vivida_, its elasticity and buoyancy, its steadfastness and resolved purpose, is the highest type of force and the image of the almighty Will. When that will is animated and filled with “the Spirit,” the man so possessed is the embodiment of an inconceivable power. Firm principle, hope and constancy, self-mastery, superiority to pleasure and pain,--all the elements of a noble courage are proper to the man of the Spirit. Such power is not neutralized by our infirmities; it asserts itself under their limiting conditions and makes them its contributories. “My grace is sufficient for thee,” said Christ to His disabled servant; “for power is perfected in weakness.” In privation and loneliness, in old age and bodily decay, the strength of God in the human spirit shines with its purest lustre. Never did St Paul rise to such a height of moral ascendency as at the time when he was “smitten down” and all but destroyed by persecution and affliction. “That the excellency of the power,” he says, “may be of God, and not from ourselves” (2 Cor. iv. 7-11). The apostle points to “the inner man” as the seat of this invigoration, thinking perhaps of its secrecy. While the world buffets and dismays the Christian, new vigour and joy are infused into his soul. The surface waters and summer brooks of comfort fail; but there opens in the heart a spring fed by the river of life proceeding from the throne of God. Beneath the toil-worn frame, the mean attire and friendless condition of the prisoner Paul--a mark for the world’s scorn--there lives a strength of thought and will mightier than the empire of the Cæsars, a power of the Spirit that is to dominate the centuries to come. Of this omnipotent power dwelling in the Church of God, the apostle prays that every one of his readers may partake.