Revelation 9:19Meaning & Commentary from the Church Fathers

It is rightly said that their stings, that is, their tails, are like serpents having heads. For the end of demonic promptings is poison-bearing sin and the death of the soul.

"From their mouths came smoke, fire, and sulfur," that is, blasphemies against God came from their mouth. "And their tails were like serpents."

By tails we mean the commanders, and by heads the princes of the world. With their help the devil does harm, and without them he cannot harm.

Either the princes of the world harm by wickedly establishing sacrilegious laws, or impious priests harm by teaching evil.

If by the horses evil spirits are understood, then Saint John rightly says that the horses' tails had heads. For the calculated consequences of demonic suggestions and incitements are poison-bearing sin and spiritual death.