„Every definition implies an axiom, since it asserts the existence of the object defined.“

—  Henri Poincaré, Context: Every definition implies an axiom, since it asserts the existence of the object defined. The definition then will not be justified, from the purely logical point of view, until we have proved that it involves no contradiction either in its terms or with the truths previously admitted. Part II. Ch. 2 : Mathematical Definitions and Education, p. 131
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Henri Poincaré14
1854 - 1912

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„The core of a root definition of a system will be a transformation process (T), the means by which defined inputs are transformed into defined outputs. The transformation will include the direct object of the main activity verbs subsequently required to describe the system.“

—  Peter Checkland British management scientist 1930
p. 223 as cited in: Gillian Ragsdell, Daune West, Jennifer Wilby (2002) Systems Theory and Practice in the Knowledge Age. p. 82. In the original quote Checkland summarised his earlier work with Smyth published in 1976.

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„A defining mark of poetry is that it defies definition.“

—  Dennis O'Driscoll Irish poet, critic 1954 - 2012
Introduction - ' The Bloodaxe Book of Poetry Quotations' ed. Dennis O'Driscoll 2006

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„A physical theory, like an abstract science, consists of definitions and axioms as first principles, and of propositions, their consequences; but with these differences:—first, That in an abstract science, a definition assigns a name to a class of notions derived originally from observation, but not necessarily corresponding to any existing objects of real phenomena, and an axiom states a mutual relation amongst such notions, or the names denoting them; while in a physical science, a definition states properties common to a class of existing objects, or real phenomena, and a physical axiom states a general law as to the relations of phenomena; and, secondly,—That in an abstract science, the propositions first discovered are the most simple; whilst in a physical theory, the propositions first discovered are in general numerous and complex, being formal laws, the immediate results of observation and experiment, from which the definitions and axioms are subsequently arrived at by a process of reasoning differing from that whereby one proposition is deduced from another in an abstract science, partly in being more complex and difficult, and partly in being to a certain extent tentative, that is to say, involving the trial of conjectural principles, and their acceptance or rejection according as their consequences are found to agree or disagree with the formal laws deduced immediately from observation and experiment.“

—  William John Macquorn Rankine civil engineer 1820 - 1872
p. 121; Second paragraph

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„The Text is not a definitive object.“

—  Roland Barthes French philosopher, critic and literary theorist 1915 - 1980
Proposition 1 Variant translation: The Text is not to be thought of as an object that can be computed. It would be futile to try to separate out materially works from texts.

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