Key Arguments

• Arendt contrasts events and ideas: prior Copernican and philosophical speculations lacked the empirical event-character and ‘objective novelty’.
• Galileo used the telescope to render what lay beyond the senses accessible ‘with the certainty of sense-perception,’ turning inspired speculation into demonstrable fact.
• The public’s stir attended Galileo’s falling bodies, but the telescope set the stage for the modern age by amalgamating astronomy and physics and enabling astrophysics.
• The Church tolerated heliocentrism as hypothesis but objected when Galileo claimed demonstration, capturing the transition from mathematical convenience to asserted reality.

Source Quotes

Ideas, moreover, as distinguished from events, are never unprecedented, and empirically unconfirmed speculations about the earth’s movement around the sun were no more unprecedented than contemporary theories about atoms would be if they had no basis in experiments and no consequences in the factual world. What Galileo did and what nobody had done before was to use the telescope in such a way that the secrets of the universe were delivered to human cognition “with the certainty of sense-perception”; that is, he put within the grasp of an earth-bound creature and its body-bound senses what had seemed forever beyond his reach, at best open to the uncertainties of speculation and imagination. This difference in relevance between the Copernican system and Galileo’s discoveries was quite clearly understood by the Catholic Church, which raised no objections to the pre-Galilean theory of an immobile sun and a moving earth as long as the astronomers used it as a convenient hypothesis for mathematical purposes; but, as Cardinal Bellarmine pointed out to Galileo, “to prove that the hypothesis . . . saves the appearances is not at all the same thing as to demonstrate the reality of the movement of the earth.”

Prior to the telescopic discoveries of Galileo, Giordano Bruno’s philosophy attracted little attention even among learned men, and without the factual confirmation they bestowed upon the Copernican revolution, not only the theologians but all “sensible men . . . would have pronounced it a wild appeal . . . of an uncontrolled imagination.” In the realm of ideas there are only originality and depth, both personal qualities, but no absolute, objective novelty; ideas come and go, they have a permanence, even an immortality of their own, depending upon their inherent power of illumination, which is and endures independently of time and history. Ideas, moreover, as distinguished from events, are never unprecedented, and empirically unconfirmed speculations about the earth’s movement around the sun were no more unprecedented than contemporary theories about atoms would be if they had no basis in experiments and no consequences in the factual world.

In the realm of ideas there are only originality and depth, both personal qualities, but no absolute, objective novelty; ideas come and go, they have a permanence, even an immortality of their own, depending upon their inherent power of illumination, which is and endures independently of time and history. Ideas, moreover, as distinguished from events, are never unprecedented, and empirically unconfirmed speculations about the earth’s movement around the sun were no more unprecedented than contemporary theories about atoms would be if they had no basis in experiments and no consequences in the factual world. What Galileo did and what nobody had done before was to use the telescope in such a way that the secrets of the universe were delivered to human cognition “with the certainty of sense-perception”; that is, he put within the grasp of an earth-bound creature and its body-bound senses what had seemed forever beyond his reach, at best open to the uncertainties of speculation and imagination.

From then on, the enthusiasm with which Giordano Bruno had conceived of an infinite universe, and the pious exultation with which Kepler had contemplated the sun, “the most excellent of all the bodies in the universe whose whole essence is nothing but pure light” and which therefore was to him the most fitting dwelling place of “God and the blessed angels,” or the more sober satisfaction of Nicholas of Cusa of seeing the earth finally at home in the starred sky, were conspicuous by their absence. By “confirming” his predecessors, Galileo established a demonstrable fact where before him there were inspired speculations. The immediate philosophic reaction to this reality was not exultation but the Cartesian doubt by which modern philosophy—that “school of suspicion,” as Nietzsche once called it—was founded, and which ended in the conviction that “only on the firm foundation of unyielding despair can the soul’s habitation henceforth be safely built.”

What Galileo did and what nobody had done before was to use the telescope in such a way that the secrets of the universe were delivered to human cognition “with the certainty of sense-perception”; that is, he put within the grasp of an earth-bound creature and its body-bound senses what had seemed forever beyond his reach, at best open to the uncertainties of speculation and imagination. This difference in relevance between the Copernican system and Galileo’s discoveries was quite clearly understood by the Catholic Church, which raised no objections to the pre-Galilean theory of an immobile sun and a moving earth as long as the astronomers used it as a convenient hypothesis for mathematical purposes; but, as Cardinal Bellarmine pointed out to Galileo, “to prove that the hypothesis . . . saves the appearances is not at all the same thing as to demonstrate the reality of the movement of the earth.” How pertinent this remark was could be seen immediately by the sudden change of mood which overtook the learned world after the confirmation of Galileo’s discovery.

Key Concepts

• What Galileo did and what nobody had done before was to use the telescope in such a way that the secrets of the universe were delivered to human cognition “with the certainty of sense-perception”;
• In the realm of ideas there are only originality and depth, both personal qualities, but no absolute, objective novelty; ideas come and go,
• Ideas, moreover, as distinguished from events, are never unprecedented, and empirically unconfirmed speculations about the earth’s movement around the sun were no more unprecedented than contemporary theories about atoms would be if they had no basis in experiments and no consequences in the factual world.
• By “confirming” his predecessors, Galileo established a demonstrable fact where before him there were inspired speculations.
• “to prove that the hypothesis . . . saves the appearances is not at all the same thing as to demonstrate the reality of the movement of the earth.”

Context

Section 36, THE DISCOVERY OF THE ARCHIMEDEAN POINT (lines 5048–5190); Arendt distinguishes Galileo’s event-like empirical breakthrough from earlier speculative cosmology.