It will help to understand the entire situation if we analyse the Article first of all and see precisely what it teaches.
1. The Spiritual Helplessness of Man. “The condition of man after the fall of Adam is such, that he cannot turn and prepare himself, by his own natural strength and good works, to faith, and calling upon God.” The Roman doctrine of Original Sin as merely a state of deprivation would naturally lead to the view that man can co-operate with Divine grace in preparation for Justification. The right exercise of free will was regarded as giving man a claim to Divine help, and this, as we shall see, was the scholastic doctrine of “congruous merit.” The view taken in the Article is that man is free, but powerless to do God’s will. 
2. The Divine Provision against Human Helplessness. “Wherefore we have no power to do good works pleasant and acceptable to God, without the grace of God by Christ.” Here the Article emphasises the need of grace, and when it speaks of good works as “pleasant and acceptable,” it obviously refers solely to those who, within the Christian revelation, are capable of considering the Divine requirements. All references to the heathen and any works of theirs are naturally ruled out in view of the historical circumstances that gave rise to the Article. The statement is concerned simply with an aspect of the spiritual life which was unduly and incorrectly emphasised in the Middle Ages.
3. The Primary Working of Divine Grace. “The grace of God by Christ preventing us, that we may have a good will.” The technical phrase implied here is “prevenient grace,” and was possibly suggested by the Latin of Psalm 59:10: “The God of my mercy will pre-vent me.” The truth is also seen in St. Paul’s words: “It is God which worketh in you both to will and to do of His good pleasure” (Phil. 2:13). The reason why grace is thus emphasised as necessary is “that we may have a good will,” and the truth is found very frequently in Holy Scripture (John 6:44; Acts 16:14).
4. The Continuous Working of Divine Grace. “And working with us, when we have that good will.” There was one slight alteration made in the English in 1571, when “working with us” was put for “working in us” as the equivalent of co-operante. The technical term for this is “co-operating grace,” and again we may refer to Holy Scripture: “The Lord also working with them” (Mark 16:20). The need of this grace is equally clear, for whether we consider the beginning, or the course, or the end of the Christian life, our Lord’s words are true: “Apart from Me ye can do nothing” (John 15:5); and St. Paul may be said to have delighted in referring everything in his life to the grace of God. “By the grace of God I am what I am” (1 Cor. 15:10; Gal. 2:20). Our Prayer Book has many similar references to this need of Divine grace. Thus, at Daily Prayer we ask: “O God, make clean our hearts within us.” In the Collect for Easter Day: “As by Thy special grace pre-venting us … so by Thy continual help.” The Collect for the Ninth Sunday after Trinity: “We, who cannot do anything that is good without Thee.” Collect for the Fourteenth Sunday after Trinity: “Make us to love that which Thou dost command.” Collect for the Fifteenth Sunday after Trinity: “The frailty of man without Thee cannot but fall.” Collect for the Seventeenth Sunday after Trinity: “Thy grace may always pre-vent and follow us.” Collect for the Nineteenth Sunday after Trinity: “Without Thee we are not able to please Thee.” Collect after Communion Office: “Pre-vent us … with Thy most gracious favour, and further us with Thy continual help.” The Homilies teach the same truth.
“It is the Holy Ghost, and no other thing, that doth quicken the minds of men, stirring up good and godly motions in their hearts, which are agreeable to the will and commandment of God, such as otherwise of their own crooked and perverse nature they should never have.”
“As for the good works of the Spirit, the fruits of faith, charitable and godly motions, if he have any at all in him, they proceed only of the Holy Ghost, who is the only worker of our sanctification, and maketh us new men in Christ Jesus.” 
“We are all become unclean, but we are not able to cleanse ourselves, nor to make one another of us clean. We are by nature the children of God’s wrath; but we are not able to make ourselves the children and inheritors of God’s glory. We are sheep that run astray, but we cannot of our own power come again to the sheepfold, so great is our imperfection and weakness.” 
>> Part 2. The History of the Article
 “And so likewise although there remain a certain freedom of will in those things which do pertain unto the desires and works of this present life (cf. Augsburg Confess., 18), yet to perform spiritual and heavenly things free will of itself is insufficient: and therefore the power of man’s free will, being thus wounded and decayed, hath need of a physician to heal it, and an help to repair it; that it may receive light and strength whereby it may see, and have power to do those godly and spiritual things, which before the fall of Adam it was able and might have done” (Necessary Doctrine and Erudition, “Article of Free Will,” pp. 360, 361).
 Homily for Whitsunday.
 Homily on the Misery of Man. See also Third Homily for Rogation Week.