O God! thou hast taught me from my youth. The Psalmist again declares the great obligations under which he lay to God for his goodness, not only with the view of encouraging himself to gratitude, but also of exciting himself to continue cherishing hope for the time to come: which will appear from the following verse. Besides, since God teaches us both by words and deeds, it is certain that the second species of teaching is here referred to, the idea conveyed being, that David had learned by continual experience, even from his infancy, that nothing is better than to lean exclusively upon the true God. That he may never be deprived of this practical truth, he testifies that he had made great proficiency in it. When he promises to become a publisher of God's wondrous works, his object in coming under this engagement is, that by his ingratitude he may not interrupt the course of the Divine beneficence. Upon the truth here stated, he rests the prayer which he presents in the 18th verse, that he may not be forgotten in his old age. His reasoning is this: Since thou, O God! hast from the commencement of my existence given me such abundant proofs of thy goodness, wilt thou not stretch forth thy hand to succor me, when now thou seest me decaying through the influence of old age? And, indeed, the conclusion is altogether inevitable, that as God vouchsafed to love us when we were infants, and embraced us with his favor when we were children, and has continued without intermission to do us good during the whole course of our life, he cannot but persevere in acting toward us in the same way even to the end. Accordingly, the particle gm, gam, which we have translated still, here signifies therefore; it being David's design, from the consideration that the goodness of God can never be exhausted, and that he is not mutable like men, to draw the inference that he will be the same towards his people in their old age, that he was towards them in their childhood. He next supports his prayer by another argument, which is, that if he should fail or faint in his old age, the grace of God, by which he had been hitherto sustained, would at the same time soon be lost sight of. If God were immediately to withdraw his grace from us after we have but just tasted it slightly, it would speedily vanish from our memory. In like manner, were he to forsake us at the close of our life, after having conferred upon us many benefits during the previous part of it, his liberality by this means would be divested of much of its interest and attraction. David therefore beseeches God to assist him even to the end, that he may be able to commend to posterity the unintermitted course of the Divine goodness, and to bear testimony, even at his very death, that God never disappoints the faithful who betake themselves to him. By the generation and those who are to come, he means the children and the children's children to whom the memorial of the loving-kindness of God cannot be transmitted unless it be perfect in all respects, and has completed its course. He mentions strength and power as the effects of God's righteousness. He is, however, to be understood by the way as eulogising by these titles the manner of his deliverance, in which he congratulates himself; as if he had said, that God, in the way in which it was accomplished, afforded a manifestation of matchless and all-sufficient power.

O God, thou hast taught me from my youth - See Psalm 71:5-6. That is, God had guided and instructed him from his earliest years. He had made known to him his own being and perfections; he had made his duty plain; he had led him along the dangerous path of life.
And hitherto have I declared - I have made known. That is, he had done this by public praise; he had done it by his writings; he had done it by maintaining and defending the truth. In all situations of life, up to that time, he had been willing to stand up for God and his cause.
Thy wondrous works - See Psalm 9:1, note; Psalm 26:7, note. Doings or acts which were suited to attract attention; to awe the mind by their greatness; to inspire confidence by their wisdom.

Thou hast taught me from my youth - I have had thee for my continual instructor: and thou didst begin to teach me thy fear and love from my tenderest infancy. Those are well taught whom God instructs; and when he teaches, there is no delay in learning.

O God, thou hast taught me from my youth,.... The corruption of human nature; the weakness and impotence of it, to everything that is spiritually good; and the need of continual strength and grace from Christ, to go to him for righteousness and strength, life and salvation, and to walk by faith on him; the doctrine of justification by the righteousness of Christ, and the insufficiency of his own; the will, ways, and worship of God; and all the duties of religion, prayer, praise, &c. and whoever were the instruments, or whatever were the means, of teaching David these things, he ascribes it to God. Whether his parents, or the priests and Levites, taught him the sacrifices and ordinances of the law, it was the Lord that blessed instructions to him; and that taught him by providences and precepts, and by his Holy Spirit. And a wonderful blessing it is to be taught of God, and not of men, things relating both to doctrine and practice; and it is an addition to it to be taught these things early, as David was from his youth; and therefore the Lord was so soon the object of his faith and trust, Psalm 71:5; and, as Timothy, from a child, was acquainted with the holy Scriptures, and the things contained in them, which are able to make wise unto salvation, Isaiah 29:13;
and hitherto have I declared thy wondrous works: not only of nature and providence, but of grace; the treasuring up of all grace, and the blessings of it in Christ; the work of redemption by him; the work of regeneration and conversion by his Spirit; and the perseverance of the saints by his grace and strength; which are all wonderful and amazing. And as the psalmist saw his interest in these things, and had an experience of them, he declared them to others for their encouragement, and to the glory of all the three Persons; see Psalm 66:16.

Past experience again encourages.
taught me, &c.--by providential dealings.