"It is a goodly device," he said, "and though I myself have, during my visit to Italy, come to believe but little in the superstitions that are held by the mass of the people, I own that my courage would have been grievously shaken if I had encountered suddenly that gibbering head. How long does the effect last?"

"Three or four days. I believe that it is a sort of slow combustion which, although it has no sensible heat, gradually consumes the particles that give rise to it. It may be that further researches will lead to a discovery by which the light might be made permanent, and in that case the invention would be a useful one. I have, however, no time to follow it up, being engaged in more serious matters, and regard this as a mere relaxation from more important work."

"And yet, methinks," the merchant said, "that were men of science, like yourself, to devote themselves to such discoveries, instead of searching for the secrets that always evade them, they might do good service to mankind. Look at this discovery of Friar Bacon's. So far, I grant that it has led to nothing, but I can see that in the future the explosive power of this powder will be turned to diverse uses besides those of machines for battering down walls. Were this light of yours made permanent it would do away with the necessity for burning lamps indoors. What could be more beautiful than a hall with its ceilings, rafters, walls, and pillars all glowing as if in the moonlight? For methinks the light resembles that of the moon rather than any other."