I was talking about eighteenth century authors prefaces and introductions a few weeks ago. here's another example of showing honest intentions from the start.

This is from what is headed The Translators Preface in The Necromancer or The Tale of the Black Forest – by Lawrence Flammenberg, translated by Peter Teuthold, Minerva, 1794.

If the subject of the following tale should be thought interesting and amusing, the public may expect a speedy publication of a still more interesting and wonderful one, exhibiting a long series of similar frauds, perpetrated under the mysterious veil of pretended supernatural aid.

In other words, if this book sells well then we will be rushing out a whole load more of the same. Very true then, and even more true now – though few publishers or authors would be so willing to state as much on the book's jacket.