This then was the provocation to that famous letter of Galileo’s to his friend and pupil Castelli, in which for the first time theological digressions occur, and which therefore, although by no means intended for publication, was to be eagerly turned to account by his opponents, and to form the groundwork of the subsequent trial. From what has been related it will be seen that the reproach often brought against Galileo that it was he who first introduced the theological question into the scientific controversy about the two systems is entirely unwarranted. On the contrary, these explanations to Castelli, of 21st December, bear telling testimony to the indignation which Galileo felt in seeing the Scriptures involved in a purely scientific discussion, and that the right of deciding the question should even be accorded to them. He sharply defines the relation in which the Bible stands to natural science, marking the limits which it can only pass at the expense of the healthy understanding of mankind. As a good Catholic he fully admits that the Scriptures cannot lie or err, but thinks that this does not hold good of all their expositors. They will involve themselves in sad contradictions, nay, even in heresies and blasphemy, if they always interpret the Bible in an absolutely literal sense. Thus, for instance, they must attribute to God hands, feet, and ears, human feelings such as anger, repentance, hatred, and make Him capable of forgetfulness and ignorance of the future. “As therefore,” continues Galileo, “the Holy Scriptures in many places not only admit but actually require a different explanation from what seems to be the literal one, it seems to me that they ought to be reserved for the last place in mathematical discussions. For they, like nature, owe their origin to the Divine Word; the former as inspired by the Holy Spirit, the latter as the fulfilment of the Divine commands; it was necessary, however, in Holy Scripture, in order to accommodate itself to the understanding of the majority, to say many things which apparently differ from the precise meaning. Nature, on the contrary, is inexorable and unchangeable, and cares not whether her hidden causes and modes of working are intelligible to the human understanding or not, and never deviates on that account from her prescribed laws. It appears to me therefore that no effect of nature, which experience places before our eyes, or is the necessary conclusion derived from evidence, should be rendered doubtful by passages of Scripture which contain thousands of words admitting of various interpretations, for every sentence of Scripture is not bound by such rigid laws as is every effect of nature.”