12 And he said that the breast and the arms of the image were of silver. This signified concerning a kingdom which was inferior to it; namely, Darius the Mede. For (God) put the kingdom into the balance. For the kingdom of the house of Nimrod was weighed and was found wanting. And since it was wanting, Darius received it. Because of this he said that his kingdom was inferior. And because it was inferior, the children of Media did not rule in all the earth. Now the belly and thighs of the image were of brass, and he said:— The third kingdom shall rule in all the earth. It is the kingdom of the children of Javan, who are children of Japhet. For the children of Javan came in against the kingdom of their brethren. For Madai and Javan are sons of Japhet. But Madai was foolish and incapable of governing the kingdom, until Javan, his brother came, who was wise and cunning, to destroy the kingdom. For Alexander, son of Philip, ruled in all the earth.
Source: Demonstrations (New Advent)