"A second type of the false position makes use of roots of negative numbers. I will give an example: If someone says to you, divide 10 into two parts, one of which multiplied into the other shall produce 30 or 40, it is evident that this case or question is impossible. Nevertheless, we shall solve it in this fashion. This, however, is closest to the quantity which is truly imaginary since operations may not be performed with it as with a pure negative number, nor as in other numbers. [...] This subtlety results from arithmetic of which this final point is, as I have said, as subtle as it is useless." (Girolamo Cardano, "The Great Rules of Algebra" ["Ars Magna" aka"Artis Magnae, sive de Regulis Algebraicis Liber Unus"], 1545)
"Although a long series of rules might be added and a long discourse given about them, we conclude our detailed consideration with the cubic, others being merely mentioned, even if generally, in passing. For as positio refers to a line, quadratum to the surface, and cubum to a solid body, it would be very foolish for us to go beyond this point. Nature does no permit it." (Girolamo Cardano, "The Great Rules of Algebra" ["Ars Magna" aka"Artis Magnae, sive de Regulis Algebraicis Liber Unus"], 1545)
"Since this art surpasses all human subtelty and the perspecuity of mortal talent and is truly a celestial gift and a very clear test of the capacity of man's minds, whoever applies himself to it will believe that there is nothing that he cannot understand." (Girolamo Cardano, "The Great Rules of Algebra" ["Ars Magna" aka"Artis Magnae, sive de Regulis Algebraicis Liber Unus"], 1545)
"The greatest advantage in gambling lies in not playing at all." (Gerolamo Cardano, "Liber de ludo aleae", cca. 1560)
"And therefore lies open the error commonly asserted that minus times minus produces plus, lest indeed it be more correct that minus times minus produces plus than plus times plus would produce minus" (Girolamo Cardano,"De Aliza Regulae", 1570)
"So shall we voyd of all craft and sail, with true reason declare how much each man erreth in life, judgement, opinion, and will. Some things there are that so wel do prove themselves, as besides nature nede no profe at all." (Girolamo Cardano, "Cardanus Comforte", 1574)
"From these beginnings, as it were, have issued bitterness, contentious obstinancy, lack of amenity, hasty judgement, anger, and an intense desire for revenge - to say nothing of headstrong will; that which many damn, by word at least, was my delight." (Girolamo Cardano, "De Vita Propria Liber" ["The Book of My Life"], 1576)
"My father, in my earliest childhood, taught me the rudiments of arithmetic, and about that time made me acquainted with the arcana; whence he had come by this learning I know not. This was about my ninth year. Shortly after, he instructed me in the elements of the astronomy of Arabia, meanwhile trying to instill in me some system of theory for memorizing, for I had been poorly endowed with the ability to remember. After I was twelve years old he taught me the first six books of Euclid, but in such a manner that he expended no effort on such parts as I was able to understand by myself. This is the knowledge I was able to acquire and learn without any elementary schooling [...]" (Girolamo Cardano, "De Vita Propria Liber" ["The Book of My Life"], 1576)
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