And the LORD said unto Moses,
Stretch out your hand toward heaven, that there may be darkness over the land of Egypt, even darkness which may be felt.
All Commentaries on Exodus 10:21 Go To Exodus 10
George Leo Haydock
Darkness upon the land of Egypt so thick that it may be felt. By means of the gross exhalations, which were to cause and accompany the darkness. (Challoner)
Thus were the Egyptians punished for keeping the Hebrews in dark prisons. (Menochius)
Philo says, even a lighted lamp or fire was extinguished. The Egyptians were affrighted with hideous spectres and evil angels. (Psalm lxxvii. 49; Wisdom xvii. 4.)