Daniel 7:6

"After this I beheld, and, lo, another, like a leopard, which had upon its back four wings of a bird; the beast had also four heads; and dominion was given to it."

This beast having four wings of a bird was thus represented as moving very rapidly; and of all the empires ever to rise in human history, Alexander's came to power with the greatest swiftness. Another factor that make it mandatory to apply this to the Macedonian-Grecian empire is the mention of four heads. This simply cannot be applied to Persia. It is obviously a prophetic reference to the four generals of Alexander the Great who founded four different empires upon the territory conquered by Alexander. This particular alone makes it impossible intellectually to identify this third beast with any other except the empire of Alexander. The proof of this is in Daniel 8:22, on which Keil made this comment:

"If the four horns of the he-goat represent four world-kingdoms rising up together, then the four heads of the leopard can never represent four kings reigning one after the other, even though it were the case, which it is not, that Daniel knew only four kings of Persia."[13]