Our song gives some hint of similar thoughts by passing from the description of the qualifications for entrance to the celebration of the security which comes from trust. The safety which is realised within the walls of the strong city is akin to the 'perfect peace' in which he who trusts is kept; and the juxtaposition of the two representations is equivalent to the teaching that trust, which is precisely the same as the New Testament faith, is the condition of entrance. We know that faith makes righteous, because it opens the heart to receive God's gift of righteousness; but that effect of faith is implied rather than stated here, where security and peace are the main ideas. As some fugitives from the storm of war sit in security behind the battlements of a fortress, and scarcely hear the din of conflict in the open field below, the heart, which has taken refuge by trust in God, is kept in peace so deep that it passes description, and the singer is fain to give a notion of its completeness by calling it 'peace, peace.' The mind which trusts is steadied thereby, as light things lashed to a firm stay are kept steadfast, however the ship toss. The only way to get and keep fixedness of temper and spirit amid change and earthquake is to hold on to God, and then we may be stable with stability derived from the foundations of His throne to which we cling. Therefore the song breaks into triumphant fervour of summons to all who hear it, to 'trust in Jab Jehovah for ever,' Such settled, perpetual trust is the only attitude corresponding to His mighty name, and to the realities found in His character. He is the 'Bock of Ages' the grand figure which Moses learned beneath the cliffs of Sinai and wove into his last song, and which tells us of the unchanging strength that makes a sure hiding-place for all generations, and the ample space which will hold all the souls of men, and be for a shadow from the heat, a covert from the tempest, a shelter from the foe, and a home for the homeless, with many a springing fountain in its clefts.