In reading through Spurgeon’s, Lectures to My Students, I came across this unforgettable story that the Prince of Preachers relayed about the value of impromptu speech:
“I remember to have been tried rather sharply on one occasion, and had I not been be versed in impromptu address, I know not how it would have sped with me. I was expected to preach in a certain chapel, and there was a crowded congregation, but I was not in time, being delayed by some blockade upon the railroad; so another minister went on with the service, and when I reached the place, all breathless with running, he was already preaching a sermon. Seeing me appear at the front door and pass up the aisle, he stopped and said, ‘There he is’, and looking at me, he added, ‘I’ll make way for you; come up and finish the sermon.’
I asked him what was the text and how far he had gone with it. He told me what the text was, and said he had just passed through the first head; without hesitation I took up the discourse at that point and finished the sermon, and I should be ashamed of any man here who could not have done the same, the circumstances being such as to make the task a remarkably easy one.
In the first place the minister was my grandfather, and, in the second place, the text was, ‘By grace are ye saved, through faith, and that not of yourselves, it is the gift of God.’ He must have been a more foolish animal than that which Balaam rode if, at such a juncture, he had not found a tongue.
‘By grace are ye saved’ had been spoken of as indicating the source of salvation; who could not follow by describing the next clause, ‘through faith’, as the channel? One did not need to study much to show that salvation is received by us through faith.
Yet, on that occasion, I had a further trial; for when I had proceeded a little, and was warming to my work, a hand patted by back approvingly, and a voice said, ‘That’s right- that’s right; tell them that again, for fear they should forget it.’ Thereupon I repeated the truth, and a little further on,when I was becoming rather deeply experimental I was gently pulled by my coat-tail, and the old gentleman stood up in front and said, ‘Now, my grandson can tell you this as a theory, but I am here to bear witness to it as a matter of practical experience: I am older than he is, and I must give you my testimony as an old man.’
Then after having given us his personal experience, he said, ‘There, now, my grandson can preach the gospel a great deal better than I can, but he cannot preach a better gospel, can he?'”
No he can’t! And nobody can! Taken from Lectures to My Students (pgs. 171,172), which is available here.