From The Doctrine of Man in Classical Lutheran Theology, eds. Herman A. Preus & Edmund Smits:
Some divergence of interpretations concerning Scriptural inspiration may be observed between the Orthodox theologians of the Lutheran and those of the Reformed Confessions. Although the latter stressed that Scripture was verbally inspired, they differed from the Lutheran writers in ascribing to it a merely instrumental function. They stoutly maintained that Holy Scripture has no power in itself; instead, it resembles some inanimate tool, a saw or a hammer, which becomes effective only when the master-workman especially designs to take it into his hands and operate with it. Thus the Holy Writings cannot work except through some special decision and operation of the Holy Spirit, who in this case “exalts” the instrument and works with it upon the listener or reader.
Lutheran Orthodox theologians did not countenance such a restriction upon the efficacy of the Holy Scriptures. In their polemical writings they emphasized the organic character of the content, designating it as a “thing which is alive” (res animata). They preferred to compare the Scriptures to the “living incorruptible seed” (I Peter 1:23), a seed that grows by itself (Mark 4:26-29), penetrating fire (Jeremiah 23:29), oil and wine (Luke 10:34), bread and food, rain that refreshes the earth, shining light, and healing medicine. Here the intrinsic value of Scripture was strongly manifested. The understanding was that the divine revelation and its expression in the Scriptures are so completely united that to divorce them would create a serious distortion. This view inspires greater confidence in the holy will of our Father in heaven than a view which leaves the inspiration of Scripture in suspense. Even the Gentiles can receive God’s light through the reading of the Holy Scriptures. No peculiar decision of the inscrutable will of God is any longer needed. God has already decided to regenerate you and has sent you his grace; the gates of revelation are not closed. Then take and read his Word, fearing only lest you should resist its power. (pp. xiii-xiv)