When we took our leave, the king spoke very kindly to Lord Lev, first by himself and then through an interpreter. He said to him these words: "I see that you come from a very distinguished family, and therefore I beg you to do our kingom the honour of asking for any gift you desire. It will be granted to you." When our lord heard this, he respectfully thanked him for the honour and favour bestowed upon him, and asked the king to give him two Moors. The king's brother was present, and when he heard this request he burst into laughter and said: "What you ask, my friend, is of no value. Ask for something greater and more honorable than these Moors. But if you desire them so much, please accept this third gift from me, a monkey, and return to your homeland, thus exquisitely endowed! Evidently," he asked, "you have neither Moors nor monkeys in your country, that you ask for them above all other things?
And when Lord Lev answered that they were seldom seen in our country, the duke said: "But there is an abundance of such things in our country. Here the king, my brother, has three cities in Africa, and sends an army into that country every year. And from no such expedition, even a smaller one, do they return empty-handed, but bring with them a hundred thousand or more Moors of all ages and sexes. And all that is brought is then sold like cattle. For such is the custom here, that people from other countries come to the Moors market and buy them up. And the king profits more from the sale of them than from the taxes of the whole kingdom. For even a small black man is worth twelve or thirteen gold pieces of Portuguese money; but a larger one is of course much more expensive." And they have a custom, that if anyone gets a strong and hard-working Moor, he baptizes him, and does not sell him, unless he gives him to a friend as a gift. But as long as the Moor is not baptized, he is free to sell him at will.
(AI translated from: Václav Šašek of Bířkov - Diary of Travels of Lord Lev of Rožmitál from Bohemia to the Edge of the World, 1467)