He maketh a path to shine after him - This refers doubtless to the white foam of the waters through which he passes. If this were spoken of some monster that commonly resides in the ocean, it would not be unnatural to suppose that it refers to the phosphoric light such as is observed when the waters are agitated, or when a vessel passes rapidly through them. If it refers, however, to the crocodile, the allusion must be understood of the hoary appearance of the Nile or the lake where he is found.
One would think the deep to be hoary - Homer often speaks of the sea as πολιὴν θάλασσαν poliēn thalassan - "the hoary sea." So Apollonius, speaking of the Argonauts, Lib. i. 545:
- μακραὶ δ ̓ αἰὲν ἐλευκαίνοντο κέλευθοι -
- makrai d' aien eleukainonto keleuthoi -
"The long paths were always white"
So Catullus, in Epith. Pelei:
Totaque remigio spumis incanuit unda.
And Ovid, Epis. Oeno:
- remis eruta canet aqua.
The rapid motion of an aquatic animal through the water will produce the effect here referred to.

He maketh a path to shine after him - In certain states of the weather a rapid motion through the water disengages many sparks of phosphoric fire. I have seen this at sea; once particularly, on a fine clear night, with a good breeze, in a fast-sailing vessel, I leaned over the stern, and watched this phenomenon for hours. The wake of the vessel was like a stream of fire; millions of particles of fire were disengaged by the ship's swift motion through the water, nearly in the same way as by the electric cushion and cylinder; and all continued to be absorbed at a short distance from the vessel. Whether this phenomenon takes place in fresh water or in the Nile, I have had no opportunity of observing.
The deep to be hoary - By the frost and foam raised by the rapid passage of the animal through the water.

He maketh a path to (l) shine after him; [one] would think the deep [to be] hoary.
(l) That is, a white froth and shining stream before him.

He maketh a path to shine after him,.... Upon the sea, by raising a white from upon it, through its vehement motion as it passes along, or by the spermaceti it casts out and leaves behind it. It is said (s) that whales will cut and plough the sea in such a manner, as to leave a shining glittering path behind them, the length of a German mile, which is three of ours;
one would think the deep to be hoary; to be old and grey headed, or white like the hair of the head of an old man, a figure often used of the sea by poets (t); and hence "Nereus" (u), which is the sea, is said to be an old man, because the froth in the waves of it looks like white hair.
(s) Vid. Scheuchzer. ibid. (vol. 4.) p. 853. (t) , Homer. Iliad. 1. v. 350. , Iliad. 4. v. 248. "incanuit unda", Catullus. (u) Phurnutus de Natura Deorum, p. 63.

path--the foam on his track.
hoary--as hair of the aged.

Shine - By the white froth or foam upon the waters. The same may be observed in the wake of a ship by night.