The juxtaposition of these passages suggests for us-- II. The twofold explanation of these variations. That bold metaphor of God's sleeping and waking is often found in Scripture, and generally expresses the contrast between the long years of patient forbearance, during which evil things and evil men go on their rebellious road unchecked but by Love, and the dread moment when some throne of iniquity, some Babylon cemented by blood, is smitten to the dust. Such is the original application of the expression here. But the contrast may fairly be widened beyond that specific form of it, and taken to express any apparent variations in the forth-putting of His power. The prophet carefully avoids seeming to suggest that there are changes in God Himself. It is not He but His arm, that is to say. His active energy, that is invoked to awake. The captive Church prays that the dormant might which could so easily shiver her prison-house would flame forth into action. We may, then, see here implied the cause of these alternations, of which we have been speaking, on its divine side, and then, in the corresponding verse addressed to the Church, the cause on the human side. As to the former, it is true that God's arm sometimes slumbers, and is not clothed with power. There are, as a fact, apparent variations in the energy with which He works in the Church and in the world. And they are real variations, not merely apparent. But we have to distinguish between the power, and what Paul calls 'the might of the power.' The one is final, constant, unchangeable. It does not necessarily follow that the other is. The rate of operation, so to speak, and the amount of energy actually brought into play may vary, though the force remains the same. It is clear from experience that there are these variations; and the only question with which we are concerned is, are they mere arbitrary jets and spurts of a divine power, sometimes gushing out in full flood, sometimes trickling in painful drops, at the unknown will of the unseen hand which controls the flow? Is the 'law of the Spirit of life' at all revealed to us; or are the reasons occult, if there be any reasons at all other than a mere will that it shall be so? Surely, whilst we never can know all the depths of His counsels and all the solemn concourse of reasons which, to speak in man's language, determine the energy of His manifested power, He has left us in no doubt that this is the weightiest part of the law which it follows--the might with which God works on the world through His Church varies according to the Church's receptiveness and faithfulness.