John Stott shares the following story from 1958 when he was leading a university outreach in Sydney, Australia. The day before the final meeting, Stott received word that his father had passed away. In addition to his grief, Stott was also starting to lose his voice. Here's how Stott describes the final day of the outreach:

It was already late afternoon within a few hours of the final meeting of the mission, so I didn't feel I could back away at that time. I went to the great hall and asked a few students to gather round me. I asked one of them to read … "My grace is sufficient for you, for my strength is made perfect in weakness," (2 Corinthians 12:8-9). A student read these verses and then I asked them to lay hands on me and … pray that those verses might be true in my own experience.

When time came for me to give my address, I preached on the [broad and narrow ways from Matthew 7]. I had to get within half an inch of the microphone, and I croaked the gospel like a raven. I couldn't exert my personality. I couldn't move. I couldn't use any inflections in my voice. I croaked the gospel in monotone. Then when the time came to give the invitation, there was an immediate response, larger than any other meeting during the mission, as students came flocking forward …

I've been back to Australia about ten times since 1958, and on every occasion somebody has come up to me and said, "Do you remember that final meeting in the university in the great hall?" "I jolly well do," I reply. "Well," they say, "I was converted that night."

Stott concludes, "The Holy Spirit takes our human words, spoken in great weakness and frailty, and he carries them home with power to the mind, the heart, the conscience, and the will of the hearers in such a way that they see and believe."