And thou shalt take this rod. There is no doubt that God chose this shepherd's rod to be the instrument of his power, in order the more to confound the pride of Pharaoh. For what but shame and reproach could it bring to Moses, that he should bear with him the crook with which he had heretofore guided his sheep in their folds and hovels? This symbol, then, of a rustic and contemptible occupation, was opposed to the scepter of Pharaoh, not without humiliation. In this respect, therefore, the obedience of Moses is worthy of praise, because he is not ashamed of a mean and humble appearance, but willingly carries his rod, and thus makes himself as nothing, and glorifies God. So is God usually wont to hide his treasures in earthen vessels, and to choose "the weak things of the world to confound the things that are mighty." But from Moses being commanded to work the miracles with the rod, we gather that outward signs are often made use of by God, when He works by His own hand; not to derogate at all from his power, or to obscure his praise, but to make it manifest that the whole world is subject to him, and that he freely applies to whatever use he pleases, things which are otherwise of no account.

Thou shalt take this rod - From the story of Moses's rod the heathens have invented the fables of the thyrsus of Bacchus, and the caduceus of Mercury. Cicero reckons five Bacchuses, one of which, according to Orpheus, was born of the river Nile; but, according to the common opinion, he was born on the banks of that river. Bacchus is expressly said to have been exposed on the river Nile, hence he is called Nilus, both by Diodorus and Macrobius; and in the hymns of Orpheus he is named Myses, because he was drawn out of the water. He is represented by the poets as being very beautiful, and an illustrious warrior; they report him to have overrun all Arabia with a numerous army both of men and women. He is said also to have been an eminent law-giver, and to have written his laws on two tables. He always carried in his hand the thyrsus, a rod wreathed with serpents, and by which he is reported to have wrought many miracles. Any person acquainted with the birth and exploits of the poetic Bacchus will at once perceive them to be all borrowed from the life and acts of Moses, as recorded in the Pentateuch; and it would be losing time to show the parallel, by quoting passages from the book of Exodus.
The caduceus or rod of Mercury is well known in poetic fables. It is another copy Of the rod of Moses. He also is reported to have wrought a multitude of miracles by this rod; and particularly he is said to kill and make alive, to send souls to the invisible world and bring them back from thence. Homer represents Mercury taking his rod to work miracles precisely in the same way as God commands Moses to take his.
Ἑρμης δε ψυχας Κυλληνιος εξεκαλειτο
Ανδρων μνηστηρων· εχε δε ῬΑΒΔΟΝ μετα χερσιν
Καλην, χρυσειην, τῃ τ' ανδρων ομματα θελγει,
Ὡν εθελει, τους δ' αυτε και ὑπνωοντας εγειρει.
Odyss., lib. xxiv., ver. 1.
Cyllenian Hermes now call'd forth the souls
Of all the suitors; with his golden Wand
Of power, to seal in balmy sleep whose eyes
Soe'er he will, and open them again.
Cowper.
Virgil copies Homer, but carries the parallel farther, tradition having probably furnished him with more particulars; but in both we may see a disguised copy of the sacred history, from which indeed the Greek and Roman poets borrowed most of their beauties.
Tum Virgam Capit: hac animas ille evocat Orco
Pallentes, alias sub tristia Tartara mittit;
Dat somnos, adimitque, et lumina morte resignat
Illa fretus agit, ventos, et turbida tranat. Aeneid, lib. iv., ver. 242.
But first he grasps within his awful hand
The mark of sovereign power, the magic wand;
With this he draws the ghosts from hollow graves,
With this he drives them down the Stygian waves;
With this he seals in sleep the wakeful sight,
And eyes, though closed in death, restores to light.
Thus arm'd, the god begins his airy race,
And drives the racking clouds along the liquid space.
Dryden.
Many other resemblances between the rod of the poets and that of Moses, the learned reader will readily recollect. These specimens may be deemed sufficient.

And thou shall take this rod in thine hand,.... Which he then had in his hand, and was no other than his shepherd's staff:
wherewith thou shall do signs: wondrous things, meaning the ten plagues inflicted on Egypt.

Take this rod - The staff or crook he carried as a shepherd, that he might not be ashamed of that mean condition out of which God called him. This rod must be his staff of authority, and must be to him instead, both of sword and sceptre.