refutes, therefore, the scientific objection to the new doctrine. Speaking of the assumed discovery of Pieroni, he says, that if it should be confirmed, however small the parallax may be, human science must draw the conclusion from it that the earth cannot be stationary in the centre. But in order to weaken this dangerous sentence, he hastens to add, that if Pieroni might be mistaken in thinking that he had discovered such a parallax of a few seconds, those might be still more mistaken who think they can observe that the visible hemisphere never varies, not even one or two seconds; for such an exact and certain observation is utterly impossible, partly from the insufficiency of the astronomical instruments, and partly from the refraction of the rays of light.
As will be seen, Galileo takes great care to show the futility of the new arguments brought into the field against the Copernican system. It therefore seems very strange that some writers, and among them the well-known Italian historian, Cesare Cantu, suppose from this letter that at the close of his life Galileo had really renounced the prohibited doctrine from profound conviction![1] The introduction, and many passages thrown in in this cautious refutation, must, as Albèri and Henri Martin justly observe, be regarded as fiction, the author having the Inquisition in view; it had recently given a striking proof of its watchfulness by forbidding the author of a book called "De Pitagorea animarum transmigratione," to apply the epithet "clarissimus" to Galileo, and it had only with great difficulty been persuaded to permit "notissimus Galileus"![2]
A short time before the close of Galileo's brilliant scientific career, in spite of age, blindness, and sickness, he once more
