Daniel 2:40

In all events Scripture says, "You, O king, were looking, and behold, one image: Great was that image and its appearance was fearful. The head of the image was of pure gold, its hands and chest and its arms were silver, the stomach and thighs were bronze, its legs were iron, the feet were part iron, part clay. You were looking until you saw a stone, which was cut without hands and it struck the image at the iron and clay feet and crushed it completely. Then once for all, the clay, iron, bronze, silver and gold were ground and they became like chaff from the summer threshing floor. And the greatness of the wind carried them away and no place was found for them. And the stone which struck the image became a great mountain and it filled all the earth. This is the dream and we will tell its interpretation before the king. You, O king, are the king of kings, to whom the God of heaven has given a strong, mighty, and honorable kingdom in every place where the sons of men dwell, and he has given into your hand beasts of the field and birds of heaven and he has ordained you Lord of all. You are the head of gold. And after you another kingdom shall arise, which is lesser than you. And a third kingdom shall arise which is bronze, which shall rule over all the earth. And a fourth kingdom will be strong as iron. In the way which iron grinds and subdues all, in this way it will grind and subdue all. And because you saw the feet and the toes, part of which were iron, part of which were clay, the kingdom shall be divided, and in it there shall be from the nature of iron, in which manner, you saw iron mixed with clay. […]

And so since the blessed Daniel described the vision and was not silent about its interpretation, he left behind some questions for those who possess a keen mind, so that again what was spoken by Daniel may be explained by another. Yet it is necessary for the lovers of truth, to not merely read cursorily, but to seek to say the obscure and to understand what was spoken by the prophets. For Daniel sees a great image, and the head of this he likens to be as pure gold. Next, the shoulders and chest he describes as being silver. Then, the stomach and thighs are bronze. Next, the legs are iron. Likewise also the toes of the feet are clay and iron which has been mixed together. Then, a stone, which is cut from a mountain without hands, strikes the image and grinds it. And the same stone became a great mountain and filled all the earth. After saying these things concerning the image, he afterwards divides the image, in accordance with its sections, into kingdoms and he explains each part of the statue, proceeding to each part, saying that the gold is king Nebuchadnezzar himself, describing him to be the golden head of the image. Next, he names a second kingdom, implying that it is inferior, saying that it is silver. Next, a third which is bronze. Then, a fourth strong kingdom, which is iron. Next, the clay and iron, having been mixed together, exhibit the tips of the feet of the image. For I have begun from the head because it displays the gold. Next, the chest and arms and he names them silver. Then, the stomach and thighs, and he indicates them to be bronze. Next, he describes the legs, and he shows them to be iron. […]

Fourth kingdom - This is the kingdom of the Romans, and was to last not only to Christ's first coming, but under antichrist, to his second coming. This did break in pieces all other kingdoms, being too strong for them, and brought all into subjection to it, 'till the stone fell upon it.

And the fourth kingdom shall be strong as iron,....

But to Nebuchadnezzar, a heathen prince, they were represented by a gay and pompous image of a man, for he was an admirer of the kingdoms of this world and the glory of them. To him the sight was so charming that he was impatient to see it again.