“The fundamental maxim of those who stand at the head of this Age, and therefore the principle of the Age, is this,—to accept nothing as really existing or obligatory, but that which they can understand and clearly comprehend. With regard to this fundamental principle, as we have now declared and adopted it without farther definition or limitation, this third Age is precisely similar to that which is to follow it, the fourth, or age of Reason as Science,—and by virtue of this similarity prepares the way for it. Before the tribunal of Science, too, nothing is accepted but the Conceivable. Only in the application of the principle there is this difference between the two Ages,—that the third, which we shall shortly name that of Empty Freedom, makes its fixed and previously acquired conceptions the measure of existence; while the fourth—that of Science—on the contrary, makes existence the measure, not of its acquired, but of its desiderated beliefs.”

I. Kandinsky's introduction
1910 - 1915, Concerning the Spiritual in Art, 1911

Géographie, in Les Oeuvres Mathématiques de Simon Stevin de Bruges (1634) ed. Girard, p. 106-108, as quoted by Jacob Klein, Greek Mathematical Thought and the Origin of Algebra (1968)

De la Ferrière, Serge Raynaud, translation from the book « Yug Yoga Yoghismo », Editorial Diana, Mexico, 1973 ; pages 686-687

Mathematical Problems (1900)
Context: History teaches the continuity of the development of science. We know that every age has its own problems, which the following age either solves or casts aside as profitless and replaces by new ones. If we would obtain an idea of the probable development of mathematical knowledge in the immediate future, we must let the unsettled questions pass before our minds and look over the problems which the science of today sets and whose solution we expect from the future. To such a review of problems the present day, lying at the meeting of the centuries, seems to me well adapted. For the close of a great epoch not only invites us to look back into the past but also directs our thoughts to the unknown future.

Source: 1930s, The conflict between Aristotelian and Galileian modes of thought in contemporary psychology, 1931, p. 153 as cited in: Eells, T. D. (2007). " Generating and generalizing knowledge about psychotherapy from pragmatic case studies http://www2.scc.rutgers.edu/journals/index.php/pcsp/article/viewFile/893/2263". In: Pragmatic Case Studies in Psychotherapy, Vol 3, Nr. 1, p. 35-54.

Thoughts on Man's Purpose in Life (1974)
Context: I do not claim to have a magic answer. But I believe there are some basic principles of existence, propounded by thinkers through the ages, which can guide us toward the goal of finding a purpose in life.
Among these principles of existence, responsibility is the one which forces man to become involved. Acceptance of responsibility means that the individual takes upon himself an obligation. Responsibility is broad and continuous. None of us are ever free of it, even if our work is unsuccessful.
Responsibility implies a commitment to self which many are not willing to make; they are strongly attracted to accepting a course of action or direction for their lives imposed by an external source. Such a relationship absolves the individual from the personal decision-making process. He wraps himself in the security blanket of inevitability or dogma, and need not invest the enormous amounts of time, effort and, above all, the thought required to make creative decisions and meaningfully participate in the governance of his life.
Responsibility also implies a commitment to others, or as Confucius taught, each of us is meant to rescue the world. It is the business of little minds to shrink from this task or to go about it without enthusiasm. Neither art, nor science, nor any of the great works of humanity would ever come into being without enthusiasm.
The sense of responsibility for doing a job right seems to be declining. In fact, the phrase "I am not responsible" has become a standard response in our society to complaints on a job poorly done. This response is a semantic error. Generally what person means is: "I cannot be held legally liable." Yet, from a moral or ethical point of view, the person who disclaims responsibility is correct: by taking this way out he is truly not responsible; he is irresponsible.

Variants: Aristocracy has three successive ages. First superiorities, then privileges and finally vanities. Having passed from the first, it degenerates in the second and dies in the third.
Aristocracy has three successive ages. First superiority, then privileges and finally vanities. Having passed from the first, it degenerates in the second and dies in the third.
Original version: L'aristocratie a trois âges successifs : l'âge des supériorités, l'âge des privilèges, l'âge des vanités ; sortie du premier, elle dégènère dans le second et s'éteint dans le dernier.
Book I, Ch. 1 : The Vallé-aux-loups
Mémoires d'outre-tombe (1848 – 1850)

Vol. I, ch. 1
History of England (1849–1861)

Heinrich Rohrer explaining how progress in miniaturization implies developing techniques in self-assembling molecular structures, in his Nishina Memorial Lecture at the University of Tokyo, on June 25, 1993. Published in [Nishina memorial lectures: creators of modern physics, Springer, 2008, 506, 4431770550]