Groves, in ancient times, were the favorite places of idolatrous worship. In the city of Rome, there were thirty-two groves consecrated to the gods. Those were commonly selected which were on hills, or high places; and they were usually furnished with temples, altars, and all the implements of idolatrous worship. Different kinds of groves were selected for this purpose, by different people. The Druids of the ancient Celtic nations in Gaul, Britain, and Germany, offered their worship in groves of oak - hence the name Druid, derived from δρῦς drus, an oak. Frequent mention is made in the Scriptures of groves and high places; and the Jews were forbidden to erect them; Deuteronomy 16:21; 1 Kings 16:23; 2 Kings 16:4; Ezekiel 6:13; Ezekiel 16:16, Ezekiel 16:39; Exodus 34:13; Judges 3:7; 1 Kings 18:19; Isaiah 17:8; Micah 5:14. When, therefore, it is said here, that they should be ashamed of the oaks, it means that they should be ashamed of their idolatrous worship, to which they were much addicted, and into which, under their wicked kings, they easily fell.