Father Grassi published a pamphlet titled An Astronomical Disputation on the Three Comets of the Year 1618 in early 1619, in which he discussed the characteristics of a comet that had appeared late the previous year in November. Grassi deduced that the comet was a blazing body that had traveled along a segment of a large circle at a constant distance from the earth, and that it was farther away than the Moon because it moved slower in the sky. Grassi's reasoning and conclusions were criticized in a subsequent paper, Discourse on Comets, published under the name of one of Galileo's pupils, a Florentine lawyer named Mario Guiducci, but largely written by Galileo himself. Galileo and Guiducci did not propose a definitive explanation for the nature of comets, but they did make some speculative hypotheses that were later proven to be incorrect. The Jesuit Christoph Scheiner was insulted gratuitously in the first line of Galileo and Guiducci's Discourse, and many disparaging remarks about the Collegio Romano's instructors were scattered throughout the book. The Jesuits were outraged, and Grassi quickly responded with his own polemical book, The Astronomical and Philosophical Balance, written under the pen name Lothario Sarsio Sigensano and claiming to be one of his own students. The Assayer was Galileo's scathing response to the Astronomical Balance. It is widely regarded as a classic of polemical prose, in which "Sarsi's" ideas are mercilessly mocked. It was well received, especially by the new pope, Urban VIII, to whom it was dedicated.