This campaign occupied a few years, but it had no sooner been launched than Sixtus produced other of the plans he had prepared in his secluded palace. I have shown how deeply the corruption of the College of Cardinals affected the religious history of Europe, and Sixtus began very quickly to reform it. It was, perhaps, not his misunderstood promise of gratitude to the cardinals who had elected him, but some feeling of incongruity with his own conduct in promoting his boy-nephews, which restrained him for a time. However that may be, he turned to the problem in the second year of his Pontificate, and his Bull _Postquam Verus_[315] laid down severe rules for the sustained improvement of the College. The number of cardinals was restricted to seventy (as is still the rule); illegitimates, and men who had sons and grandsons to favour, were excluded; and a cleric must have attained an age of at least twenty-two years before he could be promoted. In order to distribute and expedite the work of administration, he further divided the cardinals into fifteen "congregations" (some of which already existed), such as those of the Inquisition, of Public Works, of the Vatican Press, and so on. We can hardly doubt that in this division he had an ulterior aim. The earlier procedure had been for the Pope to lay a question before the whole body of the cardinals and discuss it with them. Sixtus continued to do this, but the cardinals soon found that, although he desired discussion, he turned fiery eyes, and even showered rough and offensive epithets, on any who opposed his plans. He was essentially an autocrat, and the impetuosity which was inseparable from so robust a character made him an unpleasant autocrat. The advantage to him of splitting the cardinals into small groups was that, on any grave question, he had merely to take account of the consultative opinion of a few cardinals. His more admiring biographers record that he rarely dissented from the conclusions of his congregations; in point of fact, he decided grave issues before consulting them, or made his will unmistakably clear to them. His own promotions were generally sound, though he at times strained his regulations in favour of a friend. But he greatly improved the College of Cardinals, and made an admirable effort to exclude from it nationalist influences.