This is Galileo’s argument from “The Assayer,” which I encountered in both my history survey of modern philosophy and in metaphysics. Galileo. Galileo Galilei; Il Saggiatore (The Assayer); Rome, This quietly polemical text puts the case for a pared-down scientific conception of matter and a. Il saggiatore (The assayer) by Galileo Galilei (–) is the final and most significant work in the polemic regarding the characteristics of.

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In that way you will be able to find out just how much force human authority has upon the facts of Nature, which remains deaf and inexorable to our wishes. Attacking the first conclusion with great boldness, be says that to anyone who once looked at the comet, no other argument is necessary to prove the nature of its light, for by comparison with other true lights it clearly showed itself to be real and not spurious.

The Assayer

We merely said that the proofs thus far set forth by other authors are not free from objections. Kepler tried to give a reason for the tail being really curved; Guiducci supposes it to be really straight, and seeks a cause for its bent appearance.

Anyone would make a serious error if he said that the hand, in addition to the properties of moving and touching, possessed another faculty of “tickling,” as if tickling were a phenomenon that resided in the hand that tickled. I reply that if those poets could be present at our experiments they would change their views, and without disgrace they could say they had been writing hyperbolically-or even admit they had been wrong.

Galileo proceeds by explaining the senses and their relation to elements. But with respect to the wan or any other external thing the ball does not turn at all, and does not change its tilt, and any point upon it will continue to point toward the same distant object.

I realize that often those who go about in masks are low persons who attempt by disguise to gain esteem among gentlemen and scholars, utilizing the dignity that attends nobility for some purpose of their own. Next I concede to him that this comes about from the very nature of the instrument, which must be made longer for observing nearby objects and shorter for those that are more distant.

These qualities are different from those qualities determined by our senses or secondary qualities. Natural philosophy physics spans the gamut from processes of generation and growth represented by a plant to the physical structure of the universe, represented by the cosmic cross-section. Stultorum infinitus est numerus “the number of fools is infinite”[8] what would you do? This would surely an be illuminated, but it would not change place with every motion of the observer to one side, unless perhaps he were to move several miles.


Tycho could not extricate himself from his own explanation of diversity in the apparent motion of his comet; but now Sarsi expects my mind to be satisfied and set at rest by a little poetic flower that is not followed by any fruit at all. Numerous stories are told of his skill as a mathematician and statesman, but he is best remembered in the tradition that he constructed an automaton in the form of a wooden dove which could fly. Second, I am not so sure that in order to make a comet a quasi-planet, and as such to deck it out in the attributes of other planets, it is sufficient for Sarsi or his teacher to regard it as one and so name it.

Guiducci, in the hope of doing something that would be welcome to men studious of truth, proposed with all modesty that henceforth it would be good to consider the nature of a comet, and whether it might be a mere appearance rather than a real object. Well, my part in the discovery of this instrument and whether I may reasonably claim to be its parent was long ago set forth in my Starry Messenger. This site uses cookies. Take a clean carafe and hold a lighted candle not far from it, and you will see in its surface a tiny image of the light, very sharp and bright.

The rubbing together and friction of two hard bodies, either by resolving their parts into very subtle flying particles or by opening an exit for the tiny fire-corpuscles within, ultimately sets these in motion; and when they meet our bodies and penetrate them, our conscious mind feels those pleasant or unpleasant sensations which we have named heat, burning, and scalding.

There they may learn that Archytas [10] made a dove that flew, that Archimedes made a mirror which kindled fires at great distances and many other remarkable machines, that other men have kindled perpetual fires, and a hundred more inventions no less amazing.

Sarsi next wants to make Guiducci agree with Aristotle, and to show that they have both stated the same conclusion when one of them says that motion is the cause of heat, and the other says that the cause is not motion but the brisk rubbing of two hard bodies. To say, “This body has not lost weight in the balance, and hence no part of it has been consumed,” is fallacious reasoning.

Why should I believe blindly and stupidly what I wish to believe, and subject the freedom of my intellect to someone else who is just as liable to error as I am? Hence they reasoned about it as about the other planets, to the effect that the closer Of these to the sun are the more irradiated and consequently are less enlarged when observed through the telescope.

Will he say that this comes about because they are made of different materials? Guiducci introduces a refraction not of the sun’s rays, but of the comet’s image, and not in the material of the comet but in the vaporous sphere which surrounds the earth.


Now four years after my Starry Messenger appeared, this same fellow in the habit of trying to ornament himself with other people’s works unblushingly made himself the author of the things I bad discovered and printed in that book. Before going on I wish to add something for Sarsi’s instruction. Immediately afterward I applied myself to the construction of another and better one, which six days later I took to Venice, where it was seen with great admiration by nearly all the principal gentlemen men of that republic for more than a month on end, to my considerable fatigue.

Sarsi wishes to persuade me that the fixed stars receive no appreciable enlargement from the telescope. Sounds are made and heard by us when the airwithout any special property of “sonority” or “transonority” -is ruffled by a rapid tremor into very minute waves and moves certain cartilages of a tympanum in our ear.

If this telescope merely triples the moon’s diameter, we may say that the moon is ten miles away, galikeo the sun would be fifteen if its diameter is but doubled. The same may be said of the tube of the throat, which, varying in length and breadth, accommodates itself to the formation of various notes and zssayer be said to become various tubes.

But the statement made thus far is still a long way from proving Sarsi’s point. I had written of making my first observation on the seventh of January, 16io. Guiducci has written, “Many stars completely invisible to the naked eye are made easily visible by the telescope; hence their magnification should be called infinite rather than nonexistent.

Galileo, Il Saggiatore (The Assayer)

The translation here is deliberately free. In this way he observed the resulting effect and thus discovered the instrument. If I accept Sarsi’s charge of negligence because various motions that might have been attributed to the comet did not occur to me, I fail to see how he can free his teacher from the same criticism for not considering the possibility of motion in a straight line. This extra rotation, opposite in direction to all other celestial motions, appeared to many a most improbable thing, and one that upset the whole Copernican system.

Indeed, we know that the Fleming who was first to invent the telescope was a simple maker of ordinary spectacles who, casually handling lenses of various sorts, happened to look through two at once, one convex and the other concave, and placed at different distances from the eye.