I did not do all, but I did what I could. It would have been simple to write something superficial on the topic, but the readers to whom this book is addressed would not have forgiven me for it, as they are looking for a solid base of documentation. Therefore I have proceeded in the following manner: I gave no thought to relying upon hearsay to frame my impressions. What I saw I recorded, and I wrote down only what was said to me. Imagination would have led my book astray and so destroyed its value, which is its sincerity.