He discovereth deep thirsts out of darkness - That is, God discloses truths which are wholly beyond the power of man to discover - truths that seem to be hidden in profound night. This may refer either to the revelation which God was believed to have furnished, or to his power of bringing out the most secret thoughts and purposes, or to his power of predicting future events by bringing them out of darkness to the clear light of day, or to his power of detecting plots, intrigues, and conspiracies.
And bringeth out to light the shadow of death - On the meaning of the word rendered "shadow of death," see the notes at Job 3:5. It here denotes whatever is dark or obscure. It is rather a favorite expression with the author of this poem (see Job 10:22; Job 16:16; Job 24:17; Job 34:22; Job 38:17), though it occurs elsewhere in the Scriptures. The deepest darkness, the obscurest night, are represented by it; and the idea is, that even from the most dark and impenetrable regions God could bring out light and truth. All is naked and open to the mind of God.

He discovereth deep things out of darkness - This may refer either to God's works in the great deep, or to the plots and stratagems of wicked men, conspiracies that were deeply laid, well digested, and about to be produced into existence, when death, whose shadow had hitherto concealed them, is to glut himself with carnage.

He discovereth deep things out of darkness,.... The deep things of God, his own deep things which lie in his heart, wrapped up in darkness impenetrable to creatures, and which could never be known unless he had discovered them; such as the thoughts of his heart, which are very deep, Psalm 92:5; the deep things of God, which the Spirit of God only knows, searches, and reveals, 1-Corinthians 2:10; even his thoughts of peace, and good things for his people, which are many and precious, are known to himself, and made known to them, or otherwise must have remained in darkness, and out of their reach, being as high as the heavens are from the earth; the decrees and purposes of God, which he hath purposed in himself, are deep things in his own breast, and lie concealed in darkness there, until discovered by the accomplishment of them; such as his decrees of election in Christ, redemption by him, and the effectual calling by his grace; all which are revealed and made known by the execution of them: the love of God to his people, which lay hid in his heart from everlasting; this is discovered by the gift and mission of his Son; in the regeneration and quickening of his people, and of which he makes still larger discoveries to them in the course of their lives: likewise the mysteries of the Gospel, unknown to natural men, even the wise and prudent, only known to such to whom it is given to know them, to whom they are revealed by the Father of Christ, and by the Spirit of wisdom and revelation in the knowledge of the mystery of God, and of the Father, and of Christ; respecting the persons in the Godhead, the grace of each person, the incarnation of Christ, the union of the two natures in him, redemption and justification by him, regeneration by the Spirit of God, union to Christ, and communion with him, and conformity to him in soul and body, now and hereafter: likewise the secrets of his providence, in which there is a great depth of his wisdom and knowledge, and is in great obscurity; his path is in the great waters, and his footsteps are not known; his judgments are unsearchable, and his ways past finding out, but before long they will be made manifest, and lie open to view. There are also the deep things of others, which he discovers, as the depth of sin in the deceitful heart of man, which none knows as himself; and which lie hid there until they are discovered in the light of the divine Spirit, who convinces of them, enlightens the understanding to behold those swarms of lusts and corruptions it never discerned before; and then a man comes to see and know the plague of his own heart, he was before a stranger to; also the depths of Satan, his deep laid schemes, his wiles and stratagems, to draw into sin, and so to ruin; these are unknown to natural men, but saints are made acquainted with them, so that they are not altogether ignorant of his devices, Revelation 2:24; likewise the secret plots, counsels, and combinations of wicked men, which they lay deep, and seek to hide from the Lord, being formed in the dark; but he sees and knows them, discovers and confounds them: to which may be added all the wicked actions of men done in the dark, but cannot be hid from God, with whom the darkness and the light are both alike; and who, sooner or later, brings them to light, even the hidden things of darkness, and makes manifest the counsels of the heart, as he will do more especially at the day of judgment, to which every secret thing will be brought:
and bringeth but to light the shadow of death; not only life and immortality, as by the Gospel, but death, and the shadow of it, even deadly darkness, the grossest of darkness; such who are darkness itself he makes light, and out of the darkness in them commands light to shine, as in the first creation; to them that sit in darkness, and in the shadow of death, he causes a great light to arise, the light of the Gospel, and the light of grace, yea, Christ himself, the light of the world; he calls and brings them out of it into marvellous light, out of the dark dungeon and prison of sin and unbelief, to the enjoyment of spiritual light and life here, and to everlasting light and glory hereafter.

(Daniel 2:22).

22 He discovereth deep things out of darkness,
And bringeth out to light the shadow of death;
23 He giveth prosperity to nations and then destroyeth them,
Increase of territory to nations and then carrieth them away;
24 He taketh away the understanding of the chief people of the land,
And maketh them to wander in a trackless wilderness;
25 They grope in darkness without light,
He maketh them to stagger like a drunken man.
The meaning of Job 12:22 in this connection can only be, that there is nothing so finely spun out that God cannot make it visible. All secret plans of the wicked, all secret sins, and the deeds of the evil-doer though veiled in deep darkness, He bringeth before the tribunal of the world. The form of writing given by the Masora is עמוּקות with koph raphatum, consequently plur. from עמוּק, like ערוּמים, עצוּמים from ערוּם, עצוּם, not from עמק.
(Note: Kimchi in his Wrterbuch adopts the form עמקּות, but gives Abulwalid as an authority for the lengthened form, which, according to the Masora on Leviticus 13:3, Leviticus 13:25, is the traditional. The two exceptions where the form occurs with a long vowel are Proverbs 23:27 and this passage.)
The lxx translates משגיא πλανῶν, as it is also explained in several Midrash-passages, but only by a few Jewish expositors (Jachja, Alschech) by מטעה. The word, however, is not משׁגּיא, but משׂגּיא with ש sinistrum, after which in Midrash Esther it is explained by מגדיל; and Hirzel correctly interprets it of upward growth (Jerome after the Targ. unsuitably, multiplicat), and שׁטח, on the other hand, of growth in extent. The latter word is falsely explained by the Targ. in the sense of expandere rete, and Abenezra also falsely explains: He scatters nations, and brings them to their original peace. The verb שׁטח is here connected with ל, as הפתּה (Genesis 9:27); both signify to make a wider and longer space for any one, used here of the ground where they dwell and rule. The opposite, in an unpropitious sense, is הנחה, which is used here, as 2-Kings 18:11, in a similar sense with הגלה (abducere, i.e., in servitutem). We have intentionally translated גוים nations, עם people; for גּוי, as we shall show elsewhere, is the mass held together by the ties of a common origin, language, and country; (עם) עם, the people bound together by unity of government, whose membra praecipua are consequently called העם ראשׁי. הארץ is, in this connection, the country, although elsewhere, as Isaiah 24:4, comp. Job 42:5, הארץ עם signifies also the people of the earth or mankind; for the Hebrew language expresses a country as a portion of the earth, and the earth as a whole, by the same name. Job dwells longer on this tragic picture, how God makes the star of the prosperity of these chiefs to set in mad and blind self-destruction, according to the proverb, quem Deus perdere vult prius dementat. This description seems to be echoed in many points in Isaiah, especially in the oracle on Egypt, Job 19 (e.g., כּשּׁכּור, Job 19:14). The connection ברך לא בתהו is not genitival; but דרך לא is either an adverbial clause appended to the verb, as חקר לא, Job 34:24, בנים לא, 1-Chronicles 2:30, 1-Chronicles 2:32, or, which we prefer as being more natural, and on account of the position of the words, a virtual adjective: in a trackless waste, as אישׁ לא, Job 38:26; עבות לא, 2-Samuel 23:4 (Olsh.).
Job here takes up the tone of Eliphaz (comp. Job 5:13.). Intentionally he is made to excel the friends in a recognition of the absolute majesty of God. He is not less cognizant of it than they.

Darkness - The most secret counsels of princes, which are contrived and carried on in the dark.