She perceiveth that her merchandise is good -
8. She takes care to manufacture the best articles of the kind, and to lay on a reasonable price that she may secure a ready sale. Her goods are in high repute, and she knows she can sell as much as she can make. And she finds that while she pleases her customers, she increases her own profits.
9. She is watchful and careful. Her candle - her lamp, burns all night, which is of great advantage in case of sudden alarms; and in the times and places where there were so many banditti, this was a very necessary family regulation. Perhaps some works were carried on during the night, those employed sleeping in the daytime. Thus labor never stood still; whilst some slept, others worked. This was no unusual thing in ancient times; and it prevails now; but alas! little children are often thus employed to help to support their indigent parents, and to fill the coffers of their unfeeling taskmasters.

She perceiveth that her merchandise is good,.... That it turns to good account; that her trading to heaven is of great advantage; that she grows rich hereby; that her merchandise with Wisdom, or Christ, is better than the merchandise of silver, and the gain thereby than fine gold; and though her voyages are attended with trouble and danger, yet are profitable, and therefore she is not discouraged, but determined to pursue them; she is like the merchant man, seeking goodly pearls, who finds a pearl of great price, worth all his trouble; See Gill on Proverbs 31:14 and see Proverbs 3:14;
her candle goeth not out by night; or "lamp" (s); her lamp of profession, which is always kept burning, Luke 12:35; or the glorious light of the Gospel, which always continues in the darkest times the church ever has been in; or her spiritual prosperity, which, though it may be damped, will never be extinct; when the candle of the wicked is often put out, Job 21:17; It may denote her diligence in working; who, as she rises early in the morning, Proverbs 31:15, so sits up late at night, and is never weary of well doing, night and day. Ambrose interprets it of the lamp of hope, which burns in the night, and by and for which men work, Romans 8:24.
(s) "lucerna ejus", V. L. Tigurine version, Michaelis, Schultens.

18 ט She perceiveth that her gain is good;
And her light goeth not out at night.
The perf. and fut. are related to each other as antecedent and consequent, so that 18a can also be rendered as an hypothetical antecedent. She comes to find (taste) how profitable her industry is by the experience resulting from the sale of its product: the corn, the grapes, and the wine are found to be good, and thus her gain (cf. Proverbs 3:14) is better, this opened new source of nourishment productive.
This spurs on her active industry to redoubled effort, and at times, when she is not fully occupied by the oversight of her fields and vineyard, she has another employment over which her light goes not out till far in the night. בּלּילה is, as at Lamentations 2:19, a needless Kerı̂ for the poetic בּלּיל (Isaiah 16:3). What other business it is to which she gives attention till in the night, is mentioned in the next verse.

Perceiveth - She finds great comfort in her labours. Her candle - Which is not to be taken strictly, but only signifies her unwearied care and industry.