PART II.

PUBLICATION OF THE “DIALOGUES ON THE

TWO PRINCIPAL SYSTEMS OF THE WORLD," AND

TRIAL AND CONDEMNATION OF GALILEO.

CHAPTER I.

THE "DIALOGUES" ON THE TWO SYSTEMS. Origin of the "Dialogues."-Their Popular Style.-Significance of the name Simplicius.-Hypothetical treatment of the Copernican System.Attitude of Rome towards Science.-Thomas Campanella.— Urban VIII.'s Duplicity.- Galileo takes his MS. to Rome.-Riccardi's Corrections. He gives the Imprimatur on certain Conditions. -Galileo returns to Florence to complete the Work.

IT is a curious fact that the very work which was destined to be one of the most powerful levers in obtaining general recognition for the true order of the universe originated in what we now know to be an erroneous idea. The famous book, "Dialogues on the Two Principal Systems of the World, the Ptolemaic and Copernican," arose out of the treatise on the tides which Galileo wrote at Rome, in 1616, at the suggestion of Cardinal Orsini. The important influence of these "Dialogues," both on science and the subsequent fate of the author, obliges us to discuss them more particularly.

The book contains a great deal more than is promised by the title; for the author included in it, in connection with the discussion of the two systems, nearly all the results of his researches and discoveries in science, extending over nearly fifty years. He also endeavoured to write in a style which

1 "Dialogo di Galileo: dove nei congressi di quattro giornate si discorre sopra i due Massimi Sistemi del Mondo Tolemaico e Copernicano, proponendo indeterminatamente le ragioni filosofiche e naturali tanto per l' una parte, che par l' altra."

'Comp. Galileo's letters of 7th Dec., 1624, and 12th Jan., 1630, to Cesare Marsili (Op. vi. pp. 300 and 355); also Cesi's letter to Galileo, 12th Oct., 1624 (Op. ix. p. 71).

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