THE twelve first editions of this work differ only from one another in respect of a few trifling changes. The present edition, on the contrary, has been revised and corrected with the greatest care. During the four years which have elapsed since the book appeared, I have laboured incessantly to improve it. The numerous criticisms to which it has given rise have rendered the task in certain respects an easy one. I have read all those which contain anything important. I believe I can conscientiously affirm that not once have the outrage and the calumny, which have been imported into them, hindered me from deriving profit from the just observations which those criticisms might contain. I have weighed everything, tested everything. If, in certain cases, people should wonder why I have not answered fully the censures which have been made with such extreme assurance, and as if the errors alleged have been proved, it is not that I did not know of these censures, but that it was impossible for me to accept them. In the majority of such cases I have added in a note the texts or the considerations which have deterred me from changing my opinion, or better, by making some slight change of expression, I have endeavoured to show wherein lay the contempt of my critics. These notes, though very brief and containing little more than an indication of the sources at first hand, are sufficient in every case to point out to the intelligent reader the reasonings which have guided me in the composition of my texts.