To take up some of Humboldt's headings in their order and illustrate them by quotations from Albert himself and from condensed accounts as they appear in his biographer Sighart and in Christian Schools and Scholars [Footnote 6], will serve to show at once the extent of Albert's knowledge and the presumptuous ignorance of those who make little of the science of the medieval period. When we have catalogued, for instance, the many facts with regard to astronomy and the physics of light that are supposed to have come to human ken much later, yet may be seen to have been clearly within the range of Albert's knowledge, and evidently formed the subject of his teaching at various times at both Paris and Cologne, for they are found in his authentic works, we can scarcely help but be amused at the pretentious misconception that has relegated their author to a place in education so trivial as is that which is represented in many minds by the term scholastic. [Footnote 6: Christian Schools and Scholars. Drane.] "He decides that the Milky Way is nothing but a vast {48} assemblage of stars, but supposes naturally enough that they occupy the orbit which receives the light of the sun. The figures visible on the moon's disc are not, he says, as hitherto has been supposed, reflections of the seas and mountains of the earth, but configurations of her own surface. He notices, in order to correct it, the assertion of Aristotle that lunar rainbows appear only twice in fifty years; 'I myself,' he says have observed two in a single year.' He has something to say on the refraction of a solar ray, notices certain crystals which have a power of refraction, and remarks that none of the ancients and few moderns were acquainted with the properties of mirrors." Albert's great pupil Roger Bacon is rightly looked upon as the true father of inductive science, an honor that history has unfortunately taken from him to confer it undeservedly on his namesake of four centuries later, but the teaching out of which Roger Bacon was to develop the principles of experimental science can be found in many places in his master's writings. In Albert's tenth book, wherein he catalogues and describes all the trees, plants, and herbs known in his time, he observes: "All that is here set down is the result of our own experience, or has been borrowed from authors whom we know to have written what their personal experience has confirmed: for in these matters experience alone can give certainty" (_experimentum solum certificat in talibus_). "Such an expression," says his biographer, "which might have proceeded from the pen of (Francis) Bacon, argues in itself a prodigious scientific progress, and shows that the medieval friar was on the track so successfully pursued by modern natural philosophy. He had fairly shaken off the shackles which had hitherto tied up discovery, and was the slave neither of Pliny nor of Aristotle."