This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
Q: The effect of Luther's intervention was immediate. After the sixth sermon, the Wittenberg jurist Jerome Schurf wrote to the elector: "Oh, what joy has Dr. Martin's return spread among us! His words, through divine mercy, are bringing back every day misguided people into the way of the truth."
A:
How quick was the effect of Luther's preaching?