PREFACE.

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was our labor; which was by no means equal or similar in the treatment of the words. In these, indeed, I deemed that nothing at all should be changed by me, except to replace certain terms with others where they seemed likely to bring obscurity and ambiguity to the subject matter. I also decided to name the title of the work (which for the author is On Aspects original: "de aspectibus," the traditional medieval term for perspective) by the more elegant and shorter Greek name, Optics original: "opticam".

But, most illustrious Queen Catherine de' Medici, to whom the work is dedicated, I might seem to many sophisticated men to be perhaps not unmindful of my purpose, but certainly not sufficiently mindful of your majesty, were I to discuss so many scholarly and academic matters in so scholarly a fashion in this preface to you—unless, in your name, I were bringing so singular a benefit and so popular and royal a gift to all schools and scholars. For while the benefits and gifts of outstanding kings and queens to their people can be many, certainly nothing can seem more magnificent or more royal than virtue and learning.

Indeed, if there were a place here for a rhetorician desiring to declaim on the use of optics, it would rightly seem to him a "Marathonian field" an idiom for a vast, open space for display or contest, whether the higher things of the world or these lower things are observed. For whatever has been opened and revealed to men concerning the matter, number, and order of the heavenly bodies, and the infinite variety of celestial motions, optics has almost entirely opened and revealed. Atmospheric phenomena original: "meteora," referring to everything in the sky below the moon and the miracles in the rainbow original: "iride" especially, are distinguished by optical rays. The ingenuity of optics has detected and refuted false opinions about the number, motion, and location of the elements.

In the lives of men, moreover, many things formerly attributed to the tricks of demons original: "dæmonum præstigijs," meaning magical illusions or supernatural deceptions are actually achieved by the power and faculty of the optical art. These include: representing moving images in the air, gazing upon an army separated by a great distance as if it were before one's eyes, or consuming an enemy fleet by fire a reference to the legendary "burning mirrors" of Archimedes. This is to say nothing, meanwhile, of painting, architecture, and mechanics, which are essentially nothing other than optics.

Wherefore, because Alhazen, the most ancient and comprehensive writer on optical doctrine, has been rescued from such long darkness, and—his squalor, decay, and dust wiped away—comes forth into the public light; because he enters mathematical schools; because he communicates his discoveries to public studies; for all this, to Catherine de' Medici,