=974.= I am giving this winter two courses of lectures to three students, of which one is only moderately prepared, the other less than moderately, and the third lacks both preparation and ability. Such are the onera of a mathematical profession. --GAUSS TO BESSEL, 1810. _Gauss-Bessel Briefwechsel (1880), p. 107._ =975.= Gauss once said “Mathematics is the queen of the sciences and number-theory the queen of mathematics.” If this be true we may add that the Disquisitiones is the Magna Charta of number-theory. The advantage which science gained by Gauss’ long-lingering method of publication is this: What he put into print is as true and important today as when first published; his publications are statutes, superior to other human statutes in this, that nowhere and never has a single error been detected in them. This justifies and makes intelligible the pride with which Gauss said in the evening of his life of the first larger work of his youth: “The Disquisitiones arithmeticae belong to history.” --CANTOR, M. _Allgemeine Deutsche Biographie, Bd. 8 (1878), p. 435._ =976.= Here I am at the limit which God and nature has assigned to my individuality. I am compelled to depend upon word, language and image in the most precise sense, and am wholly unable to operate in any manner whatever with symbols and numbers which are easily intelligible to the most highly gifted minds.--GOETHE. _Letter to Naumann (1826); Vogel: Goethe’s Selbstzeugnisse (Leipzig, 1903), p. 56._ =977.= Dirichlet was not satisfied to study Gauss’ “Disquisitiones arithmeticae” once or several times, but continued throughout life to keep in close touch with the wealth of deep mathematical thoughts which it contains by perusing it again and again. For this reason the book was never placed on the shelf but had an abiding place on the table at which he worked.... Dirichlet was the first one, who not only fully understood this work, but made it also accessible to others. --KUMMER, E. E. _Dirichlet: Werke, Bd. 2, p. 315._