vincingly refuted his opponent's explanation of the spots, and brilliantly defended his own right to the priority of their discovery by appealing to witnesses to whom he had made it known in 1610. These letters, together with Scheiner's, were published in March, 1613, under the title "History and Explanation of the Solar Spots,"[1] with a fine portrait of Galileo, and a dedication to his illustrious friend Salviati, of the "Accadémia dei Lincei."
The publication of this work was of especial significance, because it was the first in which Galileo decidedly takes the side of the Copernican system. This accounts for the extraordinary sensation made by these essays. The controversy on the two systems came more and more to the front. And yet, notwithstanding all this, no theological scruples seem at first to have been felt at Rome, even in the highest ecclesiastical circles. On the contrary, we find the cardinals Maffeo Barberini[2] (afterwards Pope Urban VIII), and Federigo Borromeo[3] thanking Galileo in the most friendly terms for sending them his work, and expressing their sincere admiration for the researches described in it. And Battista Agucchia, then one of the first officials at the court of Rome, and afterwards secretary of Pope Gregory XV., in a similar letter of thanks,[4] not only fully endorsed these opinions, but expressed his firm belief that they would in time be universally acknowledged, although now they had many opponents, partly from their novelty and remarkable character, and partly from the envy and obstinacy of those who had from the first maintained the contrary view.
The scientific circles of the university town of Pisa were far less friendly to the Copernican ideas than the higher ecclesiastics at the papal residence. Father Castelli, who in
