Revelation 6:8

And power was given to him over a fourth of the earth. Behold, the madness of Arius, born in Alexandria, reached as far as the Gallic Ocean, not only persecuting the pious bestially with famine of the word of God but also with physical sword. …

And behold, a pale horse, etc. Heretics who mask themselves as Catholics, worthy of the inhabiting death, drag after them a host of the lost. For the devil and his ministers are metaphorically called death and hell, as they are the cause of death and …

So the fourth seal reaches to the borders of things invisible, which are comprised in the three last seals. And power was given to him over the fourth part of the earth - What came single and in a lower degree before, comes now together, and much more severely. The first seal brought victory with it: in the second was "a great sword;" but here a scimitar.

He gave them power, that is, those instruments of his anger, or those judgments themselves; he who holds the winds in his hand has all public calamities at his command, and they can only go when he sends them and no further than he permits. To the three great judgments of war, famine, and pestilence, is here added the beasts of the earth, another of God's sore judgments, mentioned Ezek. xiv.

And I looked, and behold a pale horse,....

A pale horse - The symbol of death. Pallida mors, pale death, was a very usual poetic epithet; of this symbol there can be no doubt, because it is immediately said, His name that sat on him was Death. And hell followed with him - The grave, or state of the dead, received the slain. This is a very elegant prosopopaeia, or personification. Over the fourth part of the earth - One fourth of mankind was to feel the desolating effects of this seal.

The first seal is the summary, Christ going forth conquering till all enemies are subdued under Him, with a view to which the judgments subsequently specified accompany the preaching of the Gospel for a witness to all nations.

And I looked, and behold a pale horse - - ἵππος χλωρὸς hippos chlōros. On the horse, as an emblem, see the notes on Rev 6:2. The uniqueness of this emblem consists in the color of the horse, the rider, and the power that was given unto him. In these there is entire harmony, and there can be comparatively little difficulty in the explanation and application. The color of the horse was “pale” - χλωρὸς chlōros This word properly means “pale-green, yellowish-green,” like the color of the first shoots of grass and herbage; then green, verdant, like young herbage, Mar 6:39; Rev 8:7; Rev 9:4; and then pale yellowish (Robinson, Lexicon). The color here would be an appropriate one to denote the reign of death - as one of the most striking effects of death is paleness - and, of course, of death produced by any cause, famine, pestilence, or the sword. From this portion of the symbol, if it stood with nothing to limit and define it, we should naturally look for some condition of things in which death would prevail in a remarkable manner, or in which multitudes of human beings would be swept away. And yet, perhaps, from the very nature of this part of the symbol, we should look for the prevalence of death in some such peaceful manner as by famine or disease. The red color would more naturally denote the ravages of death in war; the black, the ravages of death by sudden calamity; the pale would more obviously suggest famine or wasting disease. And his name that sat on him was Death - No description is given of his aspect; nor does he appear with any emblem - as sword, or spear, or bow. There is evident scope for the fancy to picture to itself the form of the destroyer; and there is just that kind of obscurity about it which contributes to sublimity. […]