“Men do not care how nobly they live, but only how long, although it is within the reach of every man to live nobly, but within no man's power to live long.”

ἀλλ᾽ ἢ καλῶς ζῆν ἢ καλῶς τεθνηκέναι
τὸν εὐγενῆ χρή
Source: Ajax, Lines 479-480

Cited by a character in J. D. Salinger's The Catcher in the Rye (1951) as a statement of Stekel, this has often been attributed to Salinger, and may actually be a paraphrase by him of a statement of the German writer Otto Ludwig (1813-1865) which Stekel himself quotes in his writings:
Das Höchste, wozu er sich erheben konnte, war, für etwas rühmlich zu sterben; jetzt erhebt er sich zu dem Größern, für etwas ruhmlos zu leben.
The highest he could raise himself to was to die gloriously for something; now he rises to something greater: to live humbly for something.
Gedanken Otto Ludwigs : Aus seinem Nachlaß ausgewählt und herausgegeben von Cordelia Ludwig (1903) p. 10 http://archive.org/stream/gedankenottolud00ludwgoog#page/n39/mode/2up; this is quoted by Stekel in "Die Ausgänge der psychoanalytischen Kuren" in Zentralblatt für Psychoanalyse : Medizinische Monatsschrift für Seelenkunde (1913), p. 188 http://archive.org/stream/ZB_III_1913_4_5_k#page/n19/mode/2up, and in Das liebe Ich : Grundriss einer neuen Diätetik der Seele (1913), page 38 http://books.google.de/books?id=PgFAAAAAIAAJ&q=r%C3%BChmlich.
Misattributed

Quoted by Salinger as a statement of the psychoanalyst Wilhelm Stekel in The Catcher in the Rye, this has often been attributed to Salinger, and it may actually be a paraphrase by him of a statement of the German writer Otto Ludwig (1813-1865) which Stekel himself quotes in his writings:
Das Höchste, wozu er sich erheben konnte, war, für etwas rühmlich zu sterben; jetzt erhebt er sich zu dem Größern, für etwas ruhmlos zu leben.
The highest he could raise himself to was to die gloriously for something; now he rises to something greater: to live humbly for something.
Gedanken Otto Ludwigs : Aus seinem Nachlaß ausgewählt und herausgegeben von Cordelia Ludwig (1903), p. 10 http://archive.org/stream/gedankenottolud00ludwgoog#page/n39/mode/2up; this is quoted by Stekel in "Die Ausgänge der psychoanalytischen Kuren" in Zentralblatt für Psychoanalyse : Medizinische Monatsschrift für Seelenkunde (1913), p. 188 http://archive.org/stream/ZB_III_1913_4_5_k#page/n19/mode/2up, and in Das liebe Ich : Grundriss einer neuen Diätetik der Seele (1913), page 38 http://books.google.de/books?id=PgFAAAAAIAAJ&q=r%C3%BChmlich.
Disputed

Variant translation: It is too difficult to think nobly when one only thinks to get a living.
Source: Confessions of Jean-Jacques Rousseau (1765-1770; published 1782), Books II-VI, II
Source: Confessions

Principles of Social Reconstruction [Originally titled Why Men Fight : A Method Of Abolishing The International Duel], Ch. VIII : What We Can Do, p. 257
1910s
Context: It is preoccupation with possessions, more than anything else, that prevents men from living freely and nobly. The State and Property are the great embodiments of possessiveness; it is for this reason that they are against life, and that they issue in war. Possession means taking or keeping some good thing which another is prevented from enjoying; creation means putting into the world a good thing which otherwise no one would be able to enjoy. Since the material goods of the world must be divided among the population, and since some men are by nature brigands, there must be defensive possession, which will be regulated, in a good community, by some principle of impersonal justice. But all this is only the preface to a good life or good political institutions, in which creation will altogether outweigh possession, and distributive justice will exist as an uninteresting matter of course.
The supreme principle, both in politics and in private life, should be to promote all that is creative, and so to diminish the impulses and desires that center round possession.

Thoughts on Various Subjects from Miscellanies (1711-1726)
Variant: All would live long, but none would be old.
Source: Gulliver's Travels

The White City, l. 2-4

Window Dictatorship and Window Rights (1990) http://www1.kunsthauswien.com/english/fenster.htm