or referred to and of the correspondents who supplied notes, illustrations, and oral information includes nearly every ancient and mediæval writer who makes any reference to animals. He draws from many works which are now known only through his references, and his long list of friends and helpers includes Italians, Frenchmen, Englishmen, Germans, Swiss, and Poles.
He tells us that while it is easy to assert that history should be written from the best books only, he has found no book too bad to yield something to judicious study, and that he has ignored nothing.
"Only those who have tried," he says, "can know what a labor it is to compare the works of different authors and to bring all into unity, with nothing overlooked and nothing repeated. This I have tried to do so faithfully that all may be brought together, 
Fig. 5. a library in itself, so that no one need hereafter consult other writers on the ground which I have covered. As my only purpose," he tells us, "is to make the work more useful and accurate, I have exercised the more incredulity and have critically revised the quotations, and, when possible, verified them by original observations and dissections."
The completeness of the work is astonishing when we bear in mind that he was only thirty-five when the first part appeared, and that he had already published thirty-four works, among them two which are as remarkable as the Natural History for learning and industry, and that all the illustrations for the Natural History were prepared and the whole book written with his own hand and printed in eight years.
The dignity and thoroughness of his work are in strong contrast to many of the discursive and trivial works of his time, and his compilation was made with good judgment and independence. When he now and then quotes descriptions of fabulous or imag-
