2. Teach with a specific goal in mind.
Following the characteristics of how “the Teacher” prepared to instruct others, the author of Ecclesiastes comments on the goal for which “the Teacher” taught others. Ecclesiastes 12:11a states, “The words of the wise are like goads, their collected sayings like firmly embedded nails.” A “goad” was an implement that prodded an animal in a desired direction. A “goad” was used to direct an ox while plowing. “The Teacher’s” instruction is likened to a goad. It is intended to lead his audience to a certain place. According to 12:13 that place is genuine worship of the one true God and following his commands wholeheartedly.
This understanding does not negate that fact that a “goad” was a painful instrument. It had sharp, prickly nails fastened to the end of it to get the attention of a large animal, like an ox. “The Teacher’s” instruction was likewise difficult and painful for some of his listeners to hear. Being confronted with God’s Word may have a similar effect on people. The writer of Hebrews speaks of its ability to cut to the heart and expose us before God (Heb 4:12).
As teachers/preachers of Scripture, we should have a goal for which we are teaching others. A rather general goal would be to see our listeners conformed into the image of Christ. But we should also consider a more narrowly focused goal for each time we engage an audience with Scripture. The text should drive our goal. It may be helpful, after having surveyed the text you will be presenting, to consider developing a thesis statement for the message. You may or may not want to convey this to your audience, but at least you, the teacher/preacher will have focused the emphasis of what you are teaching and what you desire the Lord to do through your message in each listener’s life. Again, it isn’t enough to transmit information. What we should desire is a change in the hearts and minds of those to whom we teach God’s Word, change that will result in people being genuinely changed for the good, to live according to the precepts of Scripture.
3. Place your confidence in Scripture’s effectiveness to transform people.
There is a reason why we should have confidence in teaching/preaching the content of Scripture. Christian Scripture is the Word of God. Its source is divinely inspired. It’s not solely the work of human beings, but human beings who were carried along by the Spirit, so that what they recorded were truly God’s words to us (see 2 Pet 1:21). This is what the author of Ecclesiastes was alluding to when he stated, “The words of the wise … are given by one Shepherd” (Eccl 12:11b).
The words of “the Teacher” are effective ultimately for one reason. It wasn’t because of his preparation in study, nor his effectiveness as a communicator, nor the thoughtfulness with which he considered his teaching, but it had lasting effect and impact on his audience because what he taught was God’s Word.
Christian teachers and preachers may also confidently trust that what they teach is not in vain. This is because “All Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness, so that the servant of God may be thoroughly equipped for every good work” (2 Tim 3:16–17). Scripture is effective in shaping and changing those who hear it because the God who inspired Scripture is the same God who created us for him. He knows us better than we know ourselves (Ps 139). He can direct his Word to penetrate our hearts and minds and do a reforming work in us. Scripture is also the chief God-ordained means for transforming people who are lost and in rebellion against God (see Rom 10:17). This is why the Lord commands not just teachers/preachers, but all Christians to “Let the message of Christ dwell among you richly as you teach and admonish one another with all wisdom through psalms, hymns, and songs from the Spirit, singing to God with gratitude in your hearts” (Col 3:16).
This does not mean we grow slack in our preparation to teach. “The Teacher” was diligent in his preparation, even though what he taught was God’s Spirit-inspired Word. So too must Christian teachers and preachers give great care and time to being well prepared before they instruct others in the truth of God’s holy Word.
 The “firmly embedded nails” are likely a reference to the end of the “goad,” and thus the whole phrase should be taken together to refer to one image [Julie Ann Duncan, Ecclesiastes, Abingdon Old Testament Commentaries (Nashville, TN: Abingdon, 2017), 181]. Sidney Greidanus believes the phrase ought to be taken as a reference to two different items, namely “goads” and “nails” [Preaching Christ from Ecclesiastes: Foundations for Expository Sermons (Grand Rapids, MI: Eerdmans, 2010), 307]. He basis this on the two different referents to which each is paired (“words of the wise” = “goads” and “collected sayings” = “firmly embedded nails”). Words are like goads in that they are intended to move one in a certain direction, while teaching is like nails in that they give one stability and focus for one’s life.
It is difficult to determine which understanding is in view though. The question before the interpreter is how the two statements parallel one another. Is the second comparison a restatement of the first using different imagery, or are the two comparisons truly distinct from one another with each word picture conveying a different meaning?
 Peter Enns places emphasis on the goad’s ability to inflict pain. Thus, wisdom teaching is something that is painful to the listener. It is not intended to necessarily be pleasant [Ecclesiastes, The Two Horizons Old Testament Commentary (Grand Rapids, MI: Eerdmans, 2011), 112–113]. In other words, the truth hurts. See also Tremper Longman III, The Book of Ecclesiastes, NICOT (Grand Rapids, MI: Eerdmans, 1998), 279–280.
 It is possible that the author intended the reference to the “Shepherd” to refer to Solomon (or Moses), although I think this is unlikely given the addition of the modifier “one.” Solomon and all kings were shepherds of Israel, but only one would have been considered the “one Shepherd,” namely God. God is often referred to as the shepherd of Israel in the OT. Ps 23:1 is perhaps the most famous instance. God is also identified as one who gives wisdom (Prov 2:6). See Walter Kaiser, Jr., Ecclesiastes (Chicago, IL: Moody, 1979), 122–125. Longman does not believe “one Shepherd” is a reference to God (The Book of Ecclesiastes, 279). Even if Solomon is in view, as a Christian reading the OT, one must consider how Christ shapes one’s understanding of the OT. Jesus declares himself to be the “good shepherd” (John 10:11, 14). In this case, Solomon, like all the righteous Davidic kings, served as a type of Christ to come. Jesus is the fulfillment of the promise to David in 2 Samuel 7:16. In addition, like Solomon before him, what Jesus taught is worthy of listening to and obeying, since what he proclaimed is the Word of God.