Actual work upon the _Conquest_ began early in 1839, though not at first with a degree of progress which was satisfactory to the investigator. By May, however, he had warmed to his work. He went back to his old rigorous regime, giving up again all social pleasures outside of his own house, and spending in his library at least five hours each day. His period of rest had done him good, and his eyesight was now better than at any time since it first became impaired. After three months of preliminary reading he was able to sketch out the plan of the entire work, and on October 14, 1839, he began the actual task of composition. He found the introduction extremely difficult to write, for it dealt with the pre-historic period of Mexico, obscured as it was by the mist of myth and by the contradictory assertions of conflicting authorities. "The whole of that part of the story," wrote Prescott, "is in twilight, and I fear I shall at least make only moonshine of it. I must hope that it will be good moonshine. It will go hard with me, however, but that I can fish something new out of my ocean of manuscripts." He had hoped to dispose of his introduction in a hundred pages, and to finish it in six months at the most. It actually extended to two hundred and fifty pages, and the writing of it took nearly eighteen months. One interruption occurred which he had not anticipated. The success of _Ferdinand and Isabella_ had tempted an unscrupulous publisher to undertake an abridgment of that book. To protect his own interests Prescott decided to make an abridgment of his own, and thus to forestall the pirate. This work disheartened and depressed him, but he finished it with great celerity, only to find that the rival abridgment had been given up. A brief stay upon the sea-coast put him once more into working condition, and from that time he went on steadily with the _Conquest_, which he completed on August 2, 1843, not quite four years from the time when he began the actual composition. His weariness was lightened by the confidence which he felt in his own success. He knew that he had produced a masterpiece.