Kepler sent his work to Galileo, who replied in a 1596 letter, "I have for many years been a partisan of the Copernican view, because it reveals to me the causes of many natural phenomena that are otherwise incomprehensible in the light of the generally accepted hypotheses." But not until the end of his stay in Padua would Galileo devote himself fully to astronomical work, and in the 1590s he seems to have been merely lukewarm in his support of the Copernican views; his lectures continued to advance the standard arguments for an earth- centered cosmos. Meanwhile, in a portent of things to come, Kepler's writings incurred the wrath of the Catholic Church, who had begun to take a hard line on the Copernicus-Ptolemy debate, hinting that heliocentricity could not mesh with Bible's teachings on the issue. The Church had long been a center for astronomical study, and the Jesuit order in particular included many notable scientists. But by the late 16th century, the Church focused its energies everywhere on stamping out heresy; the tolerant spirit of earlier decades was on the wane. And while Protestants under Luther condemned Copernicus's ideas with equal vigor, the Catholics had the machinery in place to enforce such zeal–as Galileo would soon learn first-hand.