What does it represent?
Rome.

But this is not enough; for Rome has presented two great phases to the world, and the inquirer wants to know which one is intended by this symbol.

The answer then is, Pagan Rome; but just as soon as we add "Pagan," we introduce a religious element; for paganism is one of the mightiest systems of false religion ever devised by the arch-enemy of truth.

It was, then, the religious element in the empire that determined what symbol should be used to represent it; and the dragon represented Rome while under the control of a particular form of religion.
But the time comes when another symbol is introduced upon the scene--the leopard beast arises out of the sea.

What power is symbolized by this?
The answer is still, Rome.