Job 39:20

“Canst thou make him afraid as a grasshopper? etc.] Which is frightened at every noise, and at any approach of men; but not so the horse; or canst thou move him, or cause him to skip and jump, or rather leap like a grasshopper? that is, hast thou given, or canst thou give him the faculty of leaping over hedges and ditches, for which the horse is famous? so Neptune’s war horses are said f1405 to be euskarymoi, good leapers; the glory of his nostrils [is] terrible: which may be understood of his sneezing, snorting, pawing, and neighing, when his nostrils are broad, spread, and enlarged; and especially when enraged and in battle, when he foams and fumes, and his breath comes out of his nostrils…”

“make . . . afraid--rather, "canst thou (as I do) make him spring as the locust?" So in Joe 2:4, the comparison is between locusts and war-horses. The heads of the two are so similar that the Italians call the locusts cavaletta, "little horse." nostrils--snorting furiously.”

“Canst thou make him afraid as a grasshopper? - Or, rather, “as a locust” - כארבה kā'arbeh. This is the word which is commonly applied to the locust considered as gregarious, or as appearing in great numbers (from רבה râbâh, “to be multiplied”). On the variety of the species of locusts, see Bochart “Hieroz.” P. ii. Lib. iv. c. 1ff The Hebrew word here rendered “make afraid” (רעשׁ râ‛ash) means properly “to be moved, to be shaken,” and hence, to tremble, to be afraid. In the Hiphil, the form used here, it means to cause to tremble, to shake; and then “to cause to leap,” as a horse; and the idea here is, Canst thou cause the horse, an animal so large and powerful, to leap with the agility…”

“the glory: Job 41:20, Job 41:21; Jer 8:16 terrible: Heb. terrors Job 39:21”