Wesley's answer to enthusiasts who claimed the inward work made outward means unnecessary. The 'means of grace' — prayer, Scripture, the Lord's Supper — are the channels through which God ordinarily conveys his grace.
Sermon 16 of 44 · 1746 · Malachi 3:7
The Means of Grace
A passage from the sermon
By 'means of grace' I understand outward signs, words, or actions, ordained of God, and appointed for this end, to be the ordinary channels whereby he might convey to men, preventing, justifying, or sanctifying grace. The chief of these means are prayer, whether in secret or with the great congregation; searching the Scriptures; (which implies reading, hearing, and meditating thereon;) and receiving the Lord's Supper, eating bread and drinking wine in remembrance of him.
Whosoever therefore imagines there is any inherent power in any of these means, does greatly err, not knowing the Scriptures, neither the power of God. We know that there is no inherent power in the words spoken in prayer, in the letter of Scripture read, or the bread and wine received: but that it is God alone who is the giver of every good gift, the author of all grace; that the whole power is of him.
The full sermon is in the public domain and freely available from CCEL and other archives.