“When a great politician dies, or any man who has filled a large space in the public mind, and made a noise in the world, the newspapers long ring with the event. But it is otherwise with the great thinker, the mathematician or the philosopher, who has laboured silently and in comparative seclusion, to extend the boundaries of human knowledge. When such a man is removed by death there are public journals, even among those professedly devoted to literature and science, which can dismiss the event with a few faint and cold remarks.* But time rectifies all that. It is found sooner or later that no reputation, however brilliant, is permanent or durable which does not rest on useful discoveries and real contributions to our knowledge.”

Pt II, p. 189
Philosophical Investigations (1953)

As quoted in Madame Curie : A Biography (1937) by Eve Curie Labouisse, as translated by Vincent Sheean, p. 341
Variant translation: A scientist in his laboratory is not a mere technician: he is also a child confronting natural phenomena that impress him as though they were fairy tales.
Context: I am among those who think that science has great beauty. A scientist in his laboratory is not only a technician: he is also a child placed before natural phenomena which impress him like a fairy tale. We should not allow it to be believed that all scientific progress can be reduced to mechanisms, machines, gearings, even though such machinery also has its beauty.
Neither do I believe that the spirit of adventure runs any risk of disappearing in our world. If I see anything vital around me, it is precisely that spirit of adventure, which seems indestructible and is akin to curiosity.

Un Art de Vivre (The Art of Living) (1939), The Art of Growing Old

Source: 1930s, Education and the Social Order (1932), p. 133

Original: (de) Ein Philosoph, der keine Beziehung zur Geometrie hat, ist nur ein halber Philosoph, und ein Mathematiker, der keine philosophische Ader hat, ist nur ein halber Mathematiker.

Gottlob Frege: Erkenntnisquellen der Mathematik und der mathematischen Naturwissenschaften, 1924/1925, submitted to Wissenschaftliche Grundlagen; posthumously published in: Frege, Gottlob: Nachgelassene Schriften und Wissenschaftlicher Briefwechsel. Felix Meiner Verlag, 1990, p. 293

No. 225.
The Tatler (1711–1714)
Context: At the same time that I think discretion the most useful talent a man can be master of, I look upon cunning to be the accomplishment of little, mean, ungenerous minds. Discretion points out the noblest ends to us, and pursues the most proper and laudable methods of attaining them: cunning has only private selfish aims, and sticks at nothing which may make them succeed. Discretion has large and extended views, and, like a well-formed eye, commands a whole horizon: cunning is a kind of short-sightedness, that discovers the minutest objects which are near at hand, but is not able to discern things at a distance. Discretion the more it is discovered, gives a greater authority to the person who possesses it: cunning, when it is once detected, loses its force, and makes a man incapable of bringing about even those events which he might have done had he passed only for a plain man. Discretion is the perfection of reason, and a guide to us in all the duties of life: cunning is a kind of instinct, that only looks out after our immediate interest and welfare. Discretion is only found in men of strong sense and good understandings, cunning is often to be met with in brutes themselves, and in persons who are but the fewest removes from them.

Source: The Outsider (1956), p. 158

1920s, The Press Under a Free Government (1925)

Concerning his affair with Edwina Currie http://news.bbc.co.uk/2/hi/uk_news/politics/2286008.stm.
1990s, 1997