Further Thoughts on Revelation 13 and 17
The eighth head (Rev 17:11) is the "false prophet" or lamb-like beast of Revelation 13 which breaths life back into the mortally wounded seven headed beast. The seven headed beast is pagan Rome whose seventh head is finally slain or wounded (the Roman Empire falls). But the wound is healed as the "eighth" head which brings life back to the beast. The seven heads of the beast represent the rule of the caesars which end with the fall of the Roman Empire. The apostle Paul predicted this deadly wound to the Roman Empire in 2 Thes 2:7-8, "He who now restrains will do so until he is taken out of the way. And then the Lawless One will be revealed whom the Lord will consume with the breath of His mouth and destroy with the brightness of His coming." The false prophet (paganized Christianity) then builds an "image to the beast" and brings Rome back to life as the "Holy" Roman Empire and is ruled by the "eighth head", the Papacy (the Harlot). Finally, however, the the deceived multitudes of this unbelieving world will hate the "harlot" or "false prophet" and "eat her flesh". The meaning of this is that the Papacy falls physically during the seven last plagues when God pours out His wrath upon the "seat of the Beast" (5th plague) and the "River Euphrates is dried up" (6th plague). These plagues are symbolic or allegorical. The Papacy is totally destroyed by the brightness of Christ's coming.
The beast's description as "was, and is not, and will ascend out of the pit" refers to the healing of the deadly wound of the fallen Roman Empire to be revived as the Holy Roman Empire (the ten horns).
The seven heads of the Beast refer to the rule of the caesars, NOT the successive kingdoms of the world. This explanation also fits perfectly with the Apostle Paul's description of the "man of sin" in 2 Thes 2. and also in Act 20: 28
"Take heed therefore unto yourselves, and to all the flock, over the which the Holy Ghost hath made you overseers, to feed the church of God, which he hath purchased with his own blood. For I know this, that after my departing shall grievous wolves enter in among you, not sparing the flock. Also of your own selves shall men arise, speaking perverse things, to draw away disciples after them. Therefore watch, and remember, that by the space of three years I ceased not to warn every one night and day with tears."