AND LORD SURREY. 117 It is by no means an improbable supposition, that the mirror in that "vaulted room of gramarye" might be, strictly speaking, not a mirror, but a lens, similar to that through which the view of Scarborough was contemplated. A poet is not obliged to be minutely accurate; and, in this instance the rules of his art required him to magnify the power of the wizard. The incident is, however, said to have really happened to the earl of Surrey, while on his travels; and the poetical description does not exaggerate the power, which, in the days of Henry the Eighth, was ascribed to Cornelius Agrippa, as a magician and astrologer, who was accused by his enemies of holding frequent intercourse with departed spirits.* We have reason to be glad that we live in an age when the general diffusion of knowledge, and juster views of religious truth, would prevent any man from laying claim to magical power, or his enemies from bringing a charge against * Scott's Lay of the Last Minstrel, note, p. 336, and Lempriere's Universal Biography. 118 ACQUISITION OF KNOWLEDGE. him, that would be rejected by common sense; but though we enjoy greater advantages than were possessed by our countrymen in the days of Cornelius Agrippa, we should remember that the knowledge of other people avails us little, till, by study and reflection, we make it our own. Some diligent persons have done much more than this; and, when next I have the pleasure of seeing you, we shall notice several, who, by improving the inventions and extending the discoveries of others, so greatly enlarged the bounds of knowledge, that they are deservedly regarded as benefactors to mankind. 121 LECTURE IV. SPECTACLES AND TELESCOPES. IN our last Lecture, we began to consider the advantages resulting from the transparency of glass. I told you that we are indebted to Sir Isaac Newton's observations on the sun's rays passing through a prism, for the important discovery of the nature of light and colours. We noticed the intense heat produced when these rays are collected into a focus, either by refraction or reflection; and some curious optical deceptions, occasioned by the diverging, converging, and crossing, of certain rays of light. We amused ourselves with the effect, without fully explaining the cause, for the clear understanding of which, some acquaintance with G |