Concerning this. — Better, it, or her — i.e., Egypt.
Their strength is to sit still. — The Authorised version fairly gives the meaning: “Their boasted strength will be found absolute inaction.” but the words, as Isaiah wrote or spoke them, had a more epigrammatic point — “Rahab, they are sitting still.” He uses the poetical name for Egypt which we find in Isaiah 51:9; Job 26:12; Psalms 87:4; Psalms 89:10, and which conveyed the idea of haughty and inflated arrogance. “Rahab sitting still” was one of those mots which stamp themselves upon a nation’s memory, just as in modern times the Bourbons have been characterised as “learning nothing, forgetting nothing,” or Bismarck’s policy as one of “blood and iron.” It was, so to speak, almost a political caricature.