John Calvin Commentary Deuteronomy 17:17

"Neither shall he multiply wives to himself, that his heart turn not away: neither shall he greatly multiply to himself silver and gold." — Deuteronomy 17:17 (ASV)

Neither shall he multiply wives to himself. Polygamy at that time had generally been prevalent, so that even the most humble of the people violated the marriage vow with impunity. Therefore, it was necessary that kings should be bound by stricter restrictions, lest by their example they should give greater encouragement to incontinence.

Thus, the ignorance of those who conclude that what was specifically forbidden to kings was permitted to private individuals is easily refuted. On the contrary, the law of chastity was imposed upon kings because, without this remedy, there would be no bounds to their lasciviousness.

Besides, the people would have been subjected to great expense on account of these wives, since the ambition of women is such that they would all have desired to receive royal treatment; they would even have vied with each other in finery, as actually happened. David transgressed this law, perhaps to some extent excusably on account of his repudiation by Michal. Still, it appears that lust had more power over him than the continence prescribed by God.

Some connect what follows as if it were the reason for the preceding command: “that kings were not to multiply wives to themselves, lest their heart should turn away from what was right.” This was the case with Solomon, for by being too devoted to his wives and being deceived by the snares of women, he fell into idolatry. Indeed, it can scarcely fail to happen that when many wives beset a man, they will render his mind effeminate and stifle in him all his manly good sense.

Yet I prefer to take the clause separately: kings must beware lest the splendor of their dignity affect the soundness of their judgment. For nothing is more difficult than for one in great power to remain disposed to temperance. Therefore, God does not in vain command that they should constantly persevere in their duty and not lose their understanding.

Moreover, God forbids kings to heap up treasures, because this cannot be done without plunder and violent exactions. At the same time, wealth encourages them to audaciously undertake unjust wars, incites them to gross dissipation, and eventually drives them to tyrannical excesses. Therefore, God would first have kings beware: lest in their pursuit of riches they exhaust the blood of the people; lest they lavish their ill-gotten money on superfluous expenses and be extravagant with what belongs to others; and lastly, lest they be tempted by the pride of wealth to attempt unlawful things.