The following is from a paper I just wrote on the subject.
Edwards’s “Farewell Sermon”, delivered in June 1750 on 2 Corinthians 1:14, presents Edwards’s most extended treatment of the theology of Christian ministry, specifically, the theology of the pastorate. The following quotation captures nicely Edwards’s view of his call.
Ministers are set as guides and teachers, and are represented in Scripture as lights set up in the churches; and in the present state meet their people from time to time in order to instruct and enlighten them, to correct their mistakes, and to be a voice behind them, saying, “This is the way, walk in it” [Is. 30:21]; to evince and confirm the truth by exhibiting the proper evidences of it, and to refute errors and corrupt opinions, to convince the erroneous and establish the doubting.
For all of Edwards’s abilities and proclivities, these words are immensely instructive to the one seeking an abbreviated conception of Edwards’s understanding of his life’s work. A minister is a “light” who leads his people on the narrow path of textual faithfulness. Pastors are both “guides” and “teachers.” Though Edwards’s capacities for preaching and theological instruction are so often bifurcated, in his own mind they were united. The master pastor-theologian saw the Word as calling him to be just that: a pastor-theologian, one called to feed his people truth and to keep them from ingesting theological teaching that would poison and corrupt them.
This life-passion did not produce a thinly moralistic, intellectually simplistic body of work. No, Edwards’s sermons show that his quest to defend truth and refute error resulted in doctrinal and exegetical theology of the richest kind. Theology was not incidental to the life of the local church—it was central. Without a meaty, steady diet of it, the saints would suffer. The road to heaven would grow dark, and the people would wander off, Satan and a thousand dark angels waiting for them. But with it—with preaching of the stoutest kind, the stuff smacking of God, His character, His work, His dealings with men and all creation—the light would shine, and the people would live.
For Edwards, being a pastor-theologian was not a matter of choice, a pastoral flavor neatly tailored to his intellect and gifts. For Edwards, to be a pastor was only to be a pastor-theologian, one who devoted the full strength of his energy and ability to train his people in the way of truth. Though in the future these dual callings would split off from one another, in Edwards and his predecessors they were necessarily and beneficially joined.
 Jonathan Edwards, “Farewell Sermon” in Kimnach, Sermons of Jonathan Edwards, 217.
 Edwards offered equally helpful meditations on the pastorate in his “Notes on Scripture”: “When men read the Holy Scripture, they there may see Christ’s glory, as men see images of things by looking in a glass; so we see Christ’s glory in ordinances. Ministers are burning and shining lights, but then they don’t shine by their own light, but only reflect the light of Christ.” Jonathan Edwards, Notes on Scripture, ed. Stephen Stein, The Works of Jonathan Edwards, vol. 15 (New Haven: Yale, 1998), 320.