For thou hast possessed my reins Apparently he prosecutes the same subject, though he carries it out somewhat farther, declaring that we need not be surprised at God's knowledge of the most secret thoughts of men, since he formed their hearts and their reins. He thus represents God as sitting king in the very reins of man, as the center of his jurisdiction, and shows it ought to be no ground of wonder that all the windings and recesses of our hearts are known to him who, when we were inclosed in our mother's womb, saw us as clearly and perfectly as if we had stood before him in the light of mid-day. This may let us know the design with which David proceeds to speak of man's original formation, its scope is the same in the verse which follows, where, with some ambiguity in the terms employed, it is sufficiently clear and obvious that David means that he had been fashioned in a manner wonderful, and calculated to excite both fear and admiration, [1] so that he breaks forth into the praises of God. One great reason of the carnal security into which we fall, is our not considering how singularly we were fashioned at first by our Divine Maker. From this particular instance David is led to refer in general to all the works of God, which are just so many wonders fitted to draw our attention to him. The true and proper view to take of the works of God, as I have observed elsewhere, is that which ends in wonder. His declaration to the effect that his soul should well know these wonders, which far transcend human comprehension, means no more than that with humble and sober application he would give his attention and talents to obtaining such an apprehension of the wonderful works of God as might end in adoring the immensity of his glory. The knowledge he means, therefore, is not that which professes to comprehend what, under the name of wonders, he confesses to be incomprehensible, nor of that kind which philosophers presumptuously pretend to, as if they could solve every mystery of God, but simply that religious attention to the works of God which excites to the duty of thanksgiving.

Footnotes

1 - "Fearfully and wonderfully made Never was so terse and expressive a description of the physical conformation of man given by any human being. So fearfully are we made, that there is not an action or gesture of our bodies, which does not, apparently, endanger some muscle, vein, or sinew, the rupture of which would destroy either life or health. We are so wonderfully made, that our organization infinitely surpasses, in skill, contrivance, design, and adaptation of means to ends, the most curious and complicated piece of mechanism, not only ever executed by art and man's device, but ever conceived by the human imagination." -- Warner.

For thou hast possessed my reins - The word here rendered "possessed" means properly to "set upright," to "erect," and hence, the derivative of the verb is applied to a cane or reed, as being erect. Then the word means to found, to create, Genesis 14:19, Genesis 14:22 - as the heavens and the earth; and then, to get, to gain, to purchase, etc. Here the word seems to be used in its original sense, to make, create, etc. The idea is, not as in our translation, that God "possessed" or "owned" them but that he had "made" them, and that, "therefore," he knew all about them. The word "reins" means literally the "kidneys;" and then, it comes to denote the inward part, the mind, the soul, the seat of the desires, affections, and passions. Jeremiah 11:20. See Psalm 7:9, note; Job 19:27, note. The meaning here is, that God had made him; that the innermost recesses of his being had been constituted as they are by God; and that, "therefore," he must be able to see all that there is in the very depths of the soul, however it may be hidden from the eye of man.
Thou hast covered me in my mother's womb - The word here rendered "cover" means properly to interweave; to weave; to knit together, and the literal translation would be, "Thou hast "woven" me in my mother's womb, meaning that God had put his parts together, as one who weaves cloth, or who makes a basket. So it is rendered by DeWette and by Gesenius (Lexicon). The original word has, however, also the idea of protecting, as in a booth or hut, woven or knit together - to wit, of boughs and branches. The former signification best suits the connection; and then the sense would be, that as God had made him - as he had formed his members, and united them in a bodily frame and form before he was born - he must be able to understand all his thoughts and feelings. As he was not concealed from God before he saw the light, so he could not be anywhere.

Thou hast possessed my reins - As the Hebrews believed that the reins were the first part of the human fetus that is formed, it may here mean, thou hast laid the foundation of my being.

For thou hast (h) possessed my reins: thou hast covered me in my mother's womb.
(h) You have made me in all parts and therefore must know me.

For thou hast possessed my reins,.... His thoughts and counsels, the reins being the seat of instruction and counsel; hence God is called the trier of the reins, and searcher of the hearts of the children of men; he is the possessor or master of their most secret thoughts, and thoroughly knows them; see Psalm 7:9; they are also the seat of the affections, which are naturally sinful and inordinate, and set upon carnal and earthly things; but the Lord possesses and engrosses the affections of his people in the best sense, Psalm 73:25; moreover the reins are the seat of lust, the bed in which it is conceived and brought forth, and God knows the first motions of it there; and that the imagination of the thought of man's heart is evil continually, Genesis 6:5;
thou hast covered me in my mother's womb; with the secundine, or afterbirth, in which he carefully wrapped him, a proof of his knowledge of him, and care for him in the womb; or with skin and flesh he covered his bones with as they grew there; see Job 10:11; or the sense is, he protected and defended him in his embryo state, and when ripe for birth took him out from thence, and held him up ever since, Psalm 22:9; he had his eye on him when no other eye could see him, not even his mother that bare him, and before ever he himself saw light. The Targum is,
"thou hast founded me in my mother's womb.''

The fact that man is manifest to God even to the very bottom of his nature, and in every place, is now confirmed from the origin of man. The development of the child in the womb was looked upon by the Israelitish Chokma as one of the greatest mysteries, Ecclesiastes 11:5; and here the poet praises this coming into being as a marvellous work of the omniscient and omnipresent omnipotence of God. קנה here signifies condere; and סכך not: to cover, protect, as in Psalm 140:8; Job 40:22, prop. to cover with network, to hedge in, but: to plait, interweave, viz., with bones, sinews, and veins, like שׂכך in Job 10:11. The reins are made specially prominent in order to mark the, the seat of the tenderest, most secret emotions, as the work of Him who trieth the heart and the reins. The προσευχή becomes in Psalm 139:14 the εὐχαριστία: I give thanks unto Thee that I have wonderfully come into being under fearful circumstances, i.e., circumstances exciting a shudder, viz., of astonishment (נוראות as in Psalm 65:6). נפלה (= נפלא) is the passive to הפלה, Psalm 4:4; Psalm 17:7. Hitzig regards נפליתה (Thou hast shown Thyself wonderful), after the lxx, Syriac, Vulgate, and Jerome, as the only correct reading; but the thought which is thereby gained comes indeed to be expressed in the following line, Psalm 139:14, which sinks down into tautology in connection with this reading. `otsem (collectively equivalent to עצמים, Ecclesiastes 11:5) is the bones, the skeleton, and, starting from that idea, more generally the state of being as a sum-total of elements of being. אשׁר, without being necessarily a conjunction (Ew. 333, a), attaches itself to the suffix of עצמי. רקּם, "to be worked in different colours, or also embroidered," of the system of veins ramifying the body, and of the variegated colouring of its individual members, more particularly of the inward parts; perhaps, however, more generally with a retrospective conception of the colours of the outline following the undeveloped beginning, and of the forming of the members and of the organism in general.
(Note: In the Talmud the egg of a bird or of a reptile is called מרקּמת, when the outlines of the developed embryo are visible in it; and likewise the mole (mola), when traces of human; organization can be discerned in it.)
The mother's womb is here called not merely סתר (cf. Aeschylus' Eumenides, 665: ἐν σκοτοισι νηδύος τεθραμμένη, and the designation of the place where the foetus is formed as "a threefold darkness' in the Koran, Sur. xxxix. 8), the ē of which is retained here in pause (vid., Bttcher, Lehrbuch, 298), but by a bolder appellation תּחתּיּות ארץ, the lowest parts of the earth, i.e., the interior of the earth (vid., on Psalm 63:10) as being the secret laboratory of the earthly origin, with the same retrospective reference to the first formation of the human body out of the dust of the earth, as when Job says, Job 1:21 : "naked came I out of my mother's womb, and naked shall I return thither" - שׁמּה, viz., εἰς τὴν γῆν τὴν μητέρα πάντων, Sir. 40:1. The interior of Hades is also called בּטן שׁאול in Jonah 2:2, Sir. 51:5. According to the view of Scripture the mode of Adam's creation is repeated in the formation of every man, Job 33:6, cf. Job 33:4. The earth was the mother's womb of Adam, and the mother's womb out of which the child of Adam comes forth is the earth out of which it is taken.