His plan on this voyage was to find the mainland to the southward, of which he had heard rumours in Espanola. Before leaving Spain he had received a letter from an eminent lapidary named Ferrer who had travelled much in the east, and who assured him that if he sought gold and precious stones he must go to hot lands, and that the hotter the lands were, and the blacker the inhabitants, the more likely he was to find riches there. This was just the kind of theory to suit Columbus, and as he sailed towards the Cape Verde Islands he was already in imagination gathering gold and pearls on the shores of the equatorial continent. He stayed for about a week at the Cape Verde Islands, getting in provisions and cattle, and curiously observing the life of the Portuguese lepers who came in numbers to the island of Buenavista to be cured there by eating the flesh and bathing in the blood of turtles. It was not an inspiriting week which he spent in that dreary place and enervating climate, with nothing to see but the goats feeding among the scrub, the turtles crawling about the sand, and the lepers following the turtles. It began to tell on the health of the crew, so he weighed anchor on July 5th and stood on a southwesterly course. This third voyage, which was destined to be the most important of all, and the material for which had cost him so much time and labour, was undertaken in a very solemn and determined spirit. His health, which he had hoped to recover in Spain, had been if anything damaged by his worryings with officialdom there; and although he was only forty-seven years of age he was in some respects already an old man. He had entered, although happily he did not know it, on the last decade of his life; and was already beginning to suffer from the two diseases, gout and ophthalmia, which were soon to undermine his strength and endurance. Religion of a mystical fifteenth-century sort was deepening in him; he had undertaken this voyage in the name of the Holy Trinity; and to that theological entity he had resolved to dedicate the first new land that he should sight. For ten days light baffling winds impeded his progress; but at the end of that time the winds fell away altogether, and the voyagers found themselves in that flat equatorial calm known to mariners as the Doldrums. The vertical rays of the sun shone blisteringly down upon them, making the seams of the ships gape and causing the unhappy crews mental as well as bodily distress, for they began to fear that they had reached that zone of fire which had always been said to exist in the southern ocean.