Now we take to the aid pictures from the Revelation, and pictures from Daniel so see, how God does look upon time. A first picture:

"...I saw a beast rising up out of the sea, having seven heads and ten horns, …

 ... The beast (...) was like a leopard, his feet were like the feet of a bear, and his mouth like the mouth of a lion. ... " ( chap.13 )

With this we compare Daniel's dream, chap. 7: Four great beasts come up from the sea ( the sea of peoples) .

                1.) A lion. The empire of the Chaldean, Babylon.

2.) A bear. The empire of the Medes and Persians.

3.) A leopard with four heads. The empire of the Greek until 323 BC,

       until Alexander.

 4.) A terrible beast with ten horns. The empire of the Romans.

                                                   * * * * *

We count the years since the birth of Christ. God counts the years with the begin of the Babylonian captivity - since the loss of his people.

And he has a plan, to restore Israel again.   These here are the nations, which will have an influence on the fate of Israel.   Especially the angels are listed here.

The "beast from the sea" is an integration of those four empires:   Babylon, Medo-Persia, Greek and Rome.

The seven heads are dominions of the angels of Lucifer, who one after the other will reign in his time. The ten horns are human rulers, of which we have to speak of later.

And so: The seven heads of the beast are like an ancestral gallery of a dynasty.  

( This picture is a former  imagination,)