Here and there among men who were free from church control we have work of a better sort. In the twelfth and thirteenth centuries Abd Allatif made observations upon the natural history of Egypt which showed a truly scientific spirit, and the Emperor Frederick II attempted to promote a more fruitful study of Nature; but one of these men was abhorred as a Mussulman and the other as an infidel. Far more in accordance with the spirit of the time was the ecclesiastic Giraldus Cambrensis, whose book on the topography of Ireland bestows much attention upon the animals of the island, and rarely fails to make each contribute an appropriate moral. For example, he says that in Ireland "eagles live for so many ages that they seem to contend with eternity itself; so also the saints, having put off the old man and put on the new, obtain the blessed fruit of everlasting life." Again, he tells us: "Eagles often fly so high that their wings are scorched by the sun; so those who in the Holy Scriptures strive to unravel the deep and hidden secrets of the heavenly mysteries, beyond what is allowed, fall below, as if the wings of the presumptuous imaginations on which they are borne were scorched." In one of the great men of the following century appeared a gleam of healthful criticism: Albert the Great, in his work on the animals, dissents from the widespread belief that certain birds spring from trees and are nourished by the sap, and also from the theory that some are generated in the sea from decaying wood. But it required many generations for such scepticism to produce much effect, and we find among the illustrations in an edition of Mandeville published just before the Reformation not only careful accounts but pictured representations both of birds and of beasts produced in the fruit of trees.(15) (15) For Giraldus Cambrensis, see the edition in the Bohn Library, London, 1863, p. 30; for the Abd Allatif and Frederick II, see Hoefer, as above; for Albertus Magnus, see the De Animalibus, lib. xxiii; for the illustrations in Mandeville, see the Strasburg edition, 1484; for the history of the myth of the tree which produces birds, see Max Muller's lectures on the Science of Language, second series, lect. xii. This general employment of natural science for pious purposes went on after the Reformation. Luther frequently made this use of it, and his example controlled his followers. In 1612, Wolfgang Franz, Professor of Theology at Luther's university, gave to the world his sacred history of animals, which went through many editions. It contained a very ingenious classification, describing "natural dragons," which have three rows of teeth to each jaw, and he piously adds, "the principal dragon is the Devil." Near the end of the same century, Father Kircher, the great Jesuit professor at Rome, holds back the sceptical current, insists upon the orthodox view, and represents among the animals entering the ark sirens and griffins.