Decorative woodcut headpiece featuring symmetrical floral and foliate scrolls centered around a stylized mask or face.

TO THE MOST ILLUSTRIOUS

AND EXCELLENT

MAN, LORD ROBERT FLUDD,

most celebrated Doctor of Medicine and Philosophy,

AN Apologetic Letter

BY JOHANNES KEPLER, MATHEMATICIAN.

Distinguished Sir, your "Analytical Declaration" original: declaratio Analytica; this refers to Robert Fludd’s Veritatis Proscenium (1621), a book written to critique Kepler’s work reached my hands quite late. It found me entangled in inextricable business; so much so, that if I had ignored it entirely, no one familiar with my affairs could have blamed my silence on the stain of pride.

Nevertheless, my nature and the habit I have maintained until now conquered me—I mean, they conquered my weariness of writing and reading. I did not consider this an undignified contest, nor did I think a curious reader should be disappointed. Finally, as for that small profit which publishers seem to hunt for by irritating and inciting authors against one another, I have undertaken to facilitate it, as far as I am able, only through an appearance of honesty approved by all good men. Without further preamble, I shall run through the declaration itself—which was already quite long, seeing as you pay me back a hundredfold for my "Comparison" referring to the appendix in Kepler's Harmonice Mundi (1619) where he first compared his mathematical theories to Fludd's more mystical ones—using as concise a style as possible, and I will dissolve those points within it that seem to me to be offensive.

Page 3. In the title of your preface, I wonder what necessity drove you to respond, since I promised you nothing, asked you nothing, and objected to nothing. The matter and tone of your declaration are more like a rebuke; it is as if you were struggling, in a fit of temper, to drive away with words someone standing next to you in public who hadn't uttered a single syllable.

I considered myself established upon a speaker's platform original: pulpito while I was writing my work on Harmony Kepler's Harmonice Mundi (The Harmony of the World) and subjoining the comparison at the end; yet here you are, calling me to a moral trial. I will indeed respond to your objections, but from that platform: honesty demands the former, and equity permits the latter. You believe that one should not rightly cover up their errors with the obscurity of various colors; you recognize a hard and bold brow in those who dare such things. This beginning of your criticism is certainly laudable; I readily agree. You deny that one's own deeds or writings should be extolled through vanity and vainglory. I assent; you tax public vices with authority. It is in the public interest that studious youth and all writers listen to you. You think it unfair for anyone to sell themselves to the people by detracting from another's praise and depressing an honorable reputation—to trumpet the praises of their own works through injuries and disgrace to others with an unjust mouth. This is indeed most unfair, and contrary to both divine and human precepts. Nor should the judgment of published books be snatched away from readers by those in dispute. I say clearly that to forbid this is just and holy. You say you have written simply and sincerely, wishing to please the people; I praise this. You deny that you have blamed anyone secretly or openly. I am satisfied. I prefer to have affected no one, to have spoken no scurrilous insult against anyone, and to have gnawed at no one's reputation with the rusty tooth of envy. Regarding Cynic The Cynics were a school of ancient Greek philosophers known for their biting, harsh criticism of social norms and other people man-