32:21-29 Never did any wise man make a more frivolous and foolish excuse than that of Aaron. We must never be drawn into sin by any thing man can say or do to us; for men can but tempt us to sin, they cannot force us. The approach of Moses turned the dancing into trembling. They were exposed to shame by their sin. The course Moses took to roll away this reproach, was, not by concealing the sin, or putting any false colour upon it, but by punishing it. The Levites were to slay the ringleaders in this wickedness; yet none were executed but those who openly stood forth. Those are marked for ruin who persist in sin: those who in the morning were shouting and dancing, before night were dying. Such sudden changes do the judgments of the Lord sometimes make with sinners that are secure and jovial in their sin.

20. he took the calf which they had made, and burnt it in the fire, &c.—It has been supposed that the gold was dissolved by natron or some chemical substance. But there is no mention of solubility here, or in De 9:21; it was "burned in the fire," to cast it into ingots of suitable size for the operations which follow—"grounded to powder"; the powder of malleable metals can be ground so fine as to resemble dust from the wings of a moth or butterfly; and these dust particles will float in water for hours, and in a running stream for days. These operations of grinding were intended to show contempt for such worthless gods, and the Israelites would be made to remember the humiliating lesson by the state of the water they had drunk for a time [Napier]. Others think that as the idolatrous festivals were usually ended with great use of sweet wine, the nauseous draught of the gold dust would be a severe punishment (compare 2Ki 23:6, 15; 2Ch 15:16; 34:7).