Spurgeon once preached a sermon in the dark. Here’s the account from Lectures to My Students.
“At New Park Street, I once passed through a very singular experience, of which witnesses are present in this room. I had passed happily through all the early parts of divine service in the evening of the Sabbath, and was giving out the hymn before sermon. I opened the Bible to find the text, which I had carefully studied a the topic of discourse, when on the opposite page another passage of Scripture sprang upon me like a lion from a thicket, with vastly more power than I had felt when considering the text which I had chosen. The people were singing and I was sighing. I was in a strait betwixt two, and my mind hung as in the balances.
I was naturally desirous to run in the track which I had carefully planned, but the other text would take no refusal, and seemed to tug at my skirts, crying, “No, no, you must preach from me. God would have you follow me.” I deliberated within myself as to my duty, for I would neither be fanatical nor unbelieving, and at last I thought within myself, “Well, I should like to preach the sermon which I have prepared, and it is a great risk to run to sotruiktea new line of thought, but still as this text constrains me, it may be of the Lord, and therefore I will venture upon it, come what may.” I almost always announce my divisions very soon after the exordium, but on this occasion contrary to my usual custom, I did not do so, for a reason which some of you may probably guess. I passed through the first head with considerable liberty, speaking perfectly extemporaneously both as to thought and word The second point was dwelt upon with a consciousness of unusual quiet efficient power, but I had no idea what the third would or could be, for the text yielded no more matter just then, nor can I tell even now what I could have done had not an event occurred upon which I had never calculated. had brought myself into great difficulty by obeying what I thought to be a divine impulse, and I felt comparatively easy about it, believing that God would help me, and knowing that I could at least close the service should there be nothing more to be said. I had no need to deliberate, for in one moment we were in total darkness — the gas had gone out, and as the aisles were choked with people, and the place everywhere crowded, it wa a great peril, but a great blessing. What was I to do then?
The people we a little frightened, but I quieted them instantly by telling them not to be at all alarmed, though the gas was out, for it would soon be re-lighted; and a for myself, having no manuscript, I could speak just as well in the dark as in the light, if they would be so good as to sit and listen. Had my discourse been ever so elaborate, it would have been absurd to have continued it, a so as my plight was, I was all the less embarrassed. I turned at once mentally to the well-known text which speaks of the child of light walking in darkness, and the child of darkness walking in the light, and found appropriate remarks and illustrations pouring in upon me, and when the lamps were again lit, I saw before me an audience as rapt and subdued a ever a man beheld in his life. The odd thing of all was, that some few church-meetings afterwards, two persons came forward to make confession of their faith, who professed to have been converted that evening; but the first owed her conversion to the former part of the discourse, which was on the new text that came to me and the other trac his awakening to the latter part, which was occasioned by the sudden darkness. Thus, you see, Providence befriended me.
I cast myself upon God, and his arrangements quenched the light at the proper time for me. Some may ridicule, but I adore; others may even censure, but I rejoice. Anything is better than mechanical sermonizing, in which the direction of the Spirit is practically ignored. Every Holy Ghost preacher, I have no doubt, will have such recollections clustering around his ministry. I say, therefore, watch the course of Providence; cast yourselves upon the Lord guidance and help. If you have solemnly done your best to get a text, and the subject does not start up before you, go up into the pulpit firmly convinced that you will receive a message when the time comes, even though you have not a word at that moment.”
P102-104 of Lectures to My Students found at the above link.