Exodus 10:21 - Joseph Benson’s Commentary on the Old and New Testaments

We may observe concerning this plague, 1st, That it was a total darkness. We have reason to think, not only that the lights of heaven were clouded, but that all their fires and candles were put out by the damps or clammy vapours which were the cause of this darkness, for it is said, they saw not one another. 2d, That it was darkness which might be felt; felt in its causes by their finger-ends, so thick were the fogs; felt in its effects, (some think,) by their eyes, which were pricked with pain, and made the more sore by their rubbing them. Great pain is spoken of as the effect of that darkness, (Revelation 16:10,) which alludes to this. 3d, No doubt it was very frightful and amazing. The tradition of the Jews is, that in this darkness they were terrified by the apparition of evil spirits, or rather by dreadful sounds and murmurs which they made; and this is the plague which some think is intended, (for otherwise it is not mentioned at all here,) Psalms 78:49, “He poured upon them the fierceness of his anger, by sending evil angels among them;” for to those to whom the devil has been a deceiver, he will at length be a terror. 4th, It continued three days; six nights in one; so long they were imprisoned by those chains of darkness.