Jamieson, Fausset and Brown on Daniel 2:33

33. As the two arms of silver denote the kings of the Medes and Persians [Josephus]; and the two thighs of brass the Seleucidæ of Syria and Lagidæ of Egypt, the two leading sections into which Græco-Macedonia parted, so the two legs of iron signify the two Roman consuls [Newton]. The clay, in Da 2:41, "potter's clay," Da 2:43, "miry clay," means "earthenware," hard but brittle (compare Psa 2:9; Re 2:27, where the same image is used of the same event); the feet are stable while bearing only direct pressure, but easily broken to pieces by a blow (Da 2:34), the iron intermixed not retarding, but hastening, such a result.