John Wesley 
A Plain Account of Christian Perfection [EPUB ebook] 

What I purpose in the following papers is, to give a plain and distinct account of the steps by which I was led, during a course of many years, to embrace the doctrine of Christian perfection. This I owe to the serious part of mankind, those who desire to know all “the truth as it is in Jesus.” And these only are concerned in questions of this kind. To these I would nakedly declare the thing as it is, endeavouring all along to show, from one period to another, both what I thought, and why I thought so.
In the year 1725, being in the twenty-third year of my age, I met with Bishop Taylor’s “Rule and Exercises of Holy Living and Dying.” In reading several parts of this book, I was exceedingly affected; that part in particular which relates to purity of intention. Instantly I resolved to dedicate all my life to God, all my thoughts, and words, and actions; being thoroughly convinced, there was no medium; but that every part of my life (not some only) must either be a sacrifice to God, or myself, that is, in effect, to the devil.
Can any serious person doubt of this, or find a medium between serving God and serving the devil?
In the year 1726, I met with Kempis’s “Christian’s Pattern.” The nature and extent of inward religion, the religion of the heart, now appeared to me in a stronger light than ever it had done before. I saw, that giving even all my life to God (supposing it possible to do this, and go no farther) would profit me nothing, unless I gave my heart, yea, all my heart, to him.
I saw, that “simplicity of intention, and purity of affection, ” one design in all we speak or do, and one desire ruling all our tempers, are indeed “the wings of the soul, ” without which she can never ascend to the mount of God.