should be adapted not for the learned world alone, but which would be both intelligible and attractive to every educated person; and in this he attained complete success, for he wished by means of this book to extend as widely as possible a knowledge of the true order of nature. The form of the work was most happily chosen. The results of the researches of a lifetime were not given to the reader in a work redolent of the pedantry of the professor's chair, in which scientific demonstrations drag on with wearisome monotony, but in the lively form of dialogue, which admitted of digressions and gave the author scope for displaying his seductive eloquence, his rare skill in dialectics and biting sarcasm—in short, for his peculiarly brilliant style.
The dialogue is carried on by three interlocutors, two of whom adduce the scientific reasons for the double motion of the earth, while the third honestly tries to defend the opinions of the Aristotelian school with all the scientific means at his disposal, and as these did not suffice, with the arts of sophistry also. If he has but little success, the fault lies with the cause he advocates. Galileo gave to the defenders of the Copernican system the names of his two famous pupils and friends, neither of them then living, Filipo Salviati, of Florence, and Giovan Franceso Sagredo, senator of Venice, thereby erecting a better monument to them than he could have done in marble. Salviati is the special advocate of the Copernican theory. Sagredo takes the part of an educated layman, intelligent, impartial, and desirous to learn. The advocate of the Ptolemaic system was called briefly Simplicius, a pseudonym over which the learned have often puzzled their heads. Did he give this name of simpleton satirically to the champion of the ancient system, or was it merely an allusion to Simplicius, the commentator of Aristotle, as Galileo stated in his "Avviso al lettore?"
The selection of this name is characteristic of the ambiguous attitude which the author maintains in his "Dialogues." The sarcastic vein is obvious throughout, but is ingeniously con-
