For the first time John now explains that the horses’ power lies not only in their mouths but also in their tails. A horse’s tail is useless as a weapon; it serves only as a means to swat away pesky insects. But in the case of these horses, the tail is powerful—as were the tails of the locusts following from the fifth trumpet (Revelation 9:10). In typical devilish fashion, danger deceitfully appears when you do not expect it.
19 For the power of the horses is in their mouths and in their tails, for their tails are like serpents with heads, and by means of them they wound.