The story of how I came to preach that series may help to illustrate this matter.
I had actually determined—it seemed to me that I was being led in that way, but undoubtedly it was my own determination—to start a series of sermons on the Epistle to the Ephesians.
However, one morning while dressing, quite suddenly and in an overwhelming manner, it seemed to me that the Spirit of God was urging me to preach a series of sermons on ‘spiritual depression’.
Quite literally while I was dressing the series took order in my mind, and all I had to do was to rush as quickly as possible to put down on paper the various texts, and the order in which they had come to me, in that way.
I had never thought about preaching a series of sermons on spiritual depression; it had never occurred to me to do so; but it came just like that.
I always pay great attention to such happenings. It is a very wonderful and glorious experience apart from anything else; and I would not dare to disobey what I regard as a very definite injunction coming in that manner.
I am quite confident that the preaching of that series of sermons was dictated to me by the Spirit Himself.
Martyn Lloyd Jones, Preaching and Preachers