O God, thou hast taught me from my youth: and hitherto have I declared thy wondrous works.
O God, thou hast taught me from my youth - namely, to praise thee (cf. the second clause, and Psalms 71:18, second clause). God's power, exercised continually in the sufferer's behalf, gave him cause for praise; and God's Spirit taught his heart hitherto how to praise aright.