Revelation 9:2

"He opened the shaft of the pit" means that he revealed his own heart and taught people to sin without any fear or shame. "And smoke arose from the pit," that is, from the heart of a blasphemous people which also persecutes the church. "And the sun and air were darkened by the smoke of the pit." The sins that people constantly commit through the world obscure among them the sun of faith and of righteousness and in some produce a blindness so that they do not see the light of truth. "As smoke from a great furnace." This smoke that precedes the fire of the furnace generally refers to the last persecution, for the earlier persecution burns against the church, and then the crowd of hypocrites and unbelievers will be manifested. And outside [the church] the insanity of many caused by this smoke is already advanced.

[The devil] revealed his own heart, which sins without any fear or shame. "And smoke rose from the pit," that is, from a people that covers and obscures the church, so that it is said that "the sun and air were darkened with the smoke." It says that the sun was darkened, not that it fell to the earth. For the sins of evil and prideful persons, which are constantly being committed throughout the world, obscure the sun, that is, obscure the church and sometimes cause darkness for the saints and the righteous. For the number of the evil is so great that it is often with great difficulty that the good among them become evident.

And it was said to him, "You are given the key to the shaft of the abyss". The shaft of the abyss is called Gehenna.

Therefore, "smoke rose from the shaft", like the smoke of a great fire burning in the shaft. Indeed, the "smoke" signifies not only fire but also darkness; "for the voice of the Lord interrupting the flame of fire," (Ps. 29:7) as spoken by the prophet, is interpreted by the saints as the ending of the illuminating fire from the Gehenna's fire, leaving only the burning fire together with darkness within it.

And it is said that "the sun and the air were darkened by the smoke" of the pit; not that these elements themselves were darkened, but that those cast into the pit, filled with "darkness" due to punishment, have the "air" and the "sun" unseen. For therefore one of the holy prophets also said: "The sun will be darkened at midday," (Amos 8:9) referring to the calamities of the Jews, not to the darkening of the sun itself, but to those suffering in tribulation who do not see the sun; for the magnitude of calamities is accustomed to be filled with darkness.

And the smoke of the pit arose, like the smoke of a great furnace, etc. Proclaiming the great furnace, that is, the final persecution, the heretical madness rages, not only attempting to obscure the light of the weaker ones, who, like the air, touch the boundaries of the earth and heaven in some way, but also striving to obscure the light of the exalted ones, though not able to extinguish it. For even the elect will be led into error, if possible (Matthew XXIV).

And the fifth angel sounded the trumpet, and I saw a star fall from heaven upon the earth, and there was given to him the key of the pit of the abyss. And he opened the pit of the abyss: and the smoke of the pit arose, as the smoke of a great furnace. What is represented by the angel and the star has already been said. By the abyss are symbolized the hearts of the wicked, darkened by the darkness of errors. By the pit of the abyss, we should understand preachers of errors, for if the mouth of an abyss is a pit, it is right to symbolize by the pit those through whom the iniquity of the wicked pours out the venoms of its heart. By the key of the pit is represented temporal power, with which the old adversary unlocks the mouths of the reprobates so that they may speak wrong doctrines, and it is right for these doctrines to be compared to smoke because they turn the light of truth into darkness for themselves, and even seem to darken the brightness of faith in others. As for the great furnace, it is the Antichrist's persecution, out of which comes smoke, that is wrong doctrine, to turn the souls of those who perish into darkness. However, how can it be said that this smoke is similar to that of a great furnace whereas the Lord says concerning that tribulation, There shall be then great tribulation, etc.? [Matt. 24:21] One should know then that it is not on account of torments or false doctrines that that tribulation is said to be more terrible than all the others (among which is this "similar" one) but on account of miraculous signs through which it will deceive people more easily. And the sun and the air were darkened with the smoke of the pit. See, the fifth angel says that what the fourth had foretold would happen with the sun, the moon, and the stars, has already happened with the sun and the air.

'On this Caius objects, that according to this, the unrighteous are consumed by the locusts; whereas Scripture has said that sinners prosper and the righteous are persecuted, in the world' [Ps. lxxiii. 12 ] ; and Paul, that the faithful shall be persecuted and the evil shall flourish, deceiving and being deceived [2 Tim. iii. 12, 13].

But Hippolytus answers him, and says that the faithful, those who are persecuted by the unrighteous, at this period are to have rest, because they have been sealed; but the unrighteous who persecuted the saints, on them comes the plague of locusts; even as the Egyptians were devoured, and the Hebrews were free from the plagues, while they dwelt in one place. Thus the saints in this time are to be in well-being, even as our Lord said, When these things begin to be, be of good cheer, and lift up your heads, inasmuch as your redemption is nigh [St. Luke, xxi. 28]; that is, when plagues come on the evil, the righteous have rest. And this, that evil men deceive and are deceived [2 Tim. iii. 13], at the present day is coming to pass : that crafty men, who alter the words of the Lord and of the Scriptures after their evil thoughts, that even though at the present day they are proceeding further, yet in the end they are to be rebuked : even as Jannes and Jambres, who withstood Moses [ib. 8, 9], and afterwards were overcome and put to shame.'