On the Aristotelian front, open warfare was now declared, no holds barred. The target was not simply the theories, but also Galileo himself, suggesting that what was at play was personal envy and that a powerful element in this was, to quote Benedetto Castelli, 'those avidly desired thousand scudi', the salary, that is, of the Chief Mathematician. In Florence, between 1611 and 1613, Lodovico delle Colombe mounted a full challenge on floating bodies, spiced with official meetings, convened and then abandoned, and public experiments designed to lend it a compelling theatricality. Did the floating or failure to float of bodies in water depend on their individual forms, as the Aristotelians maintained, or on their different specific weights, as Galileo claimed? Yet again, it was Aristotle against Archimedes. To settle the issue rapidly, Galileo published the Discorso intorno alle cose che stanno in su l'acqua o che in quella si muovono [Discourse on Bodies on or in Water], which went into a second edition. It was followed by two replies from adversaries and two counter-replies written by Galileo in collaboration with Benedetto Castelli, the second of which was signed by Castelli alone in 1615. Over and above the individual issues, the conflict was once more between a mathematical approach to physics, between 'pluming the wings with the feathers of mathematics, without which it is impossible to rise even an arm's measure above the earth', and a descriptive, dogmatic procedure lacking in method. This had been felt by one of Galileo's opponents, Giorgio Coresio, who warned his readers against a philosophy that was 'new, full of radical change, and represented all things in the universe under different faces', unintentionally painting a picture worthy of the most ardent supporter.

 

At the same time, a question regarding the Sun also sparked controversy. In this dispute, Galileo was pitted against a figure of much higher standing than the provincial Aristotelians, the Swabian Jesuit, Christoph Scheiner, professor of mathematics at Ingolstadt. Under the pseudonym Apelles - alluding to the Greek painter who hid behind his own paintings to observe unseen the reactions of those looking at them - Scheiner, in three letters written to the Augsburg banker, Mark Welser, who had them published, announced the discovery of a phenomenon he described as 'almost incredible': sunspots. Were they alterations of the Sun? No, the Sun was known to be inalterable. Although the arguments he employed to demonstrate this were indeed dependent on telescopic observations, the gist of the matter was that a Jesuit, jealous custodian of tradition, would hardly have dared to cast doubt on the incorruptibility of the heavenly bodies. A sun with spots on it was almost offensive. Accordingly, those spots must have been stars, situated between the Earth and the Sun, deceptively appearing to the eye to be part of its surface. Galileo accepted Welser's challenge to take a stand, and in 1613, with the support of the Academy of the Lincei, he published his Hi story and Demonstrations concerning Sunspots and their Phenomena. In this text he refused to acknowledge Scheiner's stars, reassigning them their role of solar corruptors, continually disappearing and reappearing like a kind of cloud near the surface of the Sun, which probably drew them in a rotary motion around its axis.

 

Unusually prudent as to the true nature of sunspots, certain of knowing more what they were not than what they really were, Galileo nevertheless showed no humility in his general view of his adversaries' work. A few scientists and too many men, by now accustomed to recoil from 'every tiny little alteration' in the sky, appeared to him to be slaves of the education imposed on them and psychologically prisoners of a concept of the world dominated by ancestral fears. 'I fear that our attempt to measure the whole with our own poor means leads us into strange fantasies, and that our particular hatred of death makes fragility hateful to us.' Here the use of the first person was obviously a euphemism for the third. Rising above this kind of scientific infancy, Galileo flourished his own idea of knowledge, which consisted not of 'penetrating the true and intrinsic essence' of each individual natural phenomenon, leaping inconclusively from one to another, but of collocating their causes within a general world system, linking them and explaining one by another. In this way the study of sunspots had led him, step by step, to affirm the similarity of heavenly and terrestrial bodies and to hypothesise the rotation of the Sun around its own axis, a rotation that was transmitted to the bodies near it.

 

More and more pieces were being put together to form the mosaic, including rotation of Venus around the Sun, by then fully revealed, 'in accordance with the positions of Pythagoreans and Copernicus.' Aristotle and Ptolemy were tottering. For Galileo, contemporary philosophy had now become a 'great untuned organ' and from his superior height he looked down on the 'many organists striving in vain to bring it into perfect tune.' He saw them failing because they had left 'untuned three or four of the main organ-pipes', which prevented the perfection of the general harmony. To be treated as a deaf organ-tuner must have been highly annoying to Scheiner, and, behind the subsequent controversy as to which of them had been first to observe the sunspots, there probably lurked other factors.

 

This hidden rancour was to grow in time into fierce mutual contempt, so that over twenty years later Galileo, having abandoned his romantic musical metaphors, was to refer to Scheiner as a 'loathsome animal', 'pig and malevolent ass', 'contemptible little man', 'miserable wretch', whose 'childish babblings' it was a waste of time to pursue. In comparison, the lack of an ear for music was a trifling matter. The controversy with Scheiner officially inaugurated Galileo's hostile relationship with the Jesuits, destined to weigh heavily on his studies and his life. But, as he was soon to realise, it was not only the Jesuits whom he had to guard against.