You, O king, saw, and behold a great image. This great image, whose brightness was excellent, stood before you; and its form was frightening.
All Commentaries on Daniel 2:31 Go To Daniel 2
Jerome
AD 420
"The head of gold," he says "is thou, O king." By this statement it is clear that the first empire, the Babylonian, is compared to the most precious metal, gold.