I will fan them with a fan. — The image is, of course, the familiar one of the threshing-floor and the winnowing-fan or shovel (Psalms 1:4; Psalms 35:5; Matthew 3:12). The tenses should be past in both clauses — I have winnowed... I have bereaved... I have destroyed.
In the gates of the land... — Possibly the “gates” stand for the fortified cities of Judah, the chief part being taken for the whole, more probably for the “approaches” of the land. So the Greeks spoke of the passes of the Taurus as the Cilician gates, and so we speak of the Khyber and Bolam passes as “the gates of India.”
Since they return not. — The insertion of the conjunction, which has nothing corresponding to it in the original, weakens the vigour of the abruptness of the clause, and probably suggests a wrong sequence of thought. Jehovah had chastened them, but it was in vain. They returned not from their ways. Yet, as in the Vulgate, rather than “since,” is the implied conjunction.