From the book:

To equip so small a book with a preface is, I am half afraid, to sin against proportion. But a preface is more than an author can resist, for it is the reward of his labours. When the foundation stone is laid, the architect appears with his plans, and struts for an hour before the public eye. So with the writer in his preface: he may have never a word to say, but he must show himself for a moment in the portico, hat in hand, and with an urbane demeanour. It is best, in such circumstances, to represent a delicate shade of manner between humility and superiority: as if the book had been written by some one else, and you had merely run over it and inserted what was good. But for my part I have not yet learned the trick to that perfection; I am not yet able to dissemble the warmth of my sentiments towards a reader; and if I meet him on the threshold, it is to invite him in with country cordiality.