“Sometimes solve a new difficulty, leads to the unexpected solution of another hitherto unresolved difficulty.”

Source: Philosophy At The Limit (1990), Chapter 1, The Faces of Silence, p. 9

In page=89
Remembering Our Leaders: Mahadeo Govind Ranade by Pravina Bhim Sain

Original: (it) Qualsiasi difficoltà, piccola o grande che sia, stimola l'intelletto a trovare una soluzione.
Source: prevale.net

Letter to Frénicle (1657) Oeuvres de Fermat Vol.II as quoted by Edward Everett Whitford, The Pell Equation http://books.google.com/books?id=L6QKAAAAYAAJ (1912)
Context: There is scarcely any one who states purely arithmetical questions, scarcely any who understands them. Is this not because arithmetic has been treated up to this time geometrically rather than arithmetically? This certainly is indicated by many works ancient and modern. Diophantus himself also indicates this. But he has freed himself from geometry a little more than others have, in that he limits his analysis to rational numbers only; nevertheless the Zetcica of Vieta, in which the methods of Diophantus are extended to continuous magnitude and therefore to geometry, witness the insufficient separation of arithmetic from geometry. Now arithmetic has a special domain of its own, the theory of numbers. This was touched upon but only to a slight degree by Euclid in his Elements, and by those who followed him it has not been sufficiently extended, unless perchance it lies hid in those books of Diophantus which the ravages of time have destroyed. Arithmeticians have now to develop or restore it. To these, that I may lead the way, I propose this theorem to be proved or problem to be solved. If they succeed in discovering the proof or solution, they will acknowledge that questions of this kind are not inferior to the more celebrated ones from geometry either for depth or difficulty or method of proof: Given any number which is not a square, there also exists an infinite number of squares such that when multiplied into the given number and unity is added to the product, the result is a square.

A Conversation with Ward Cunningham (2003), The Simplest Thing that Could Possibly Work
Context: The complexity that we despise is the complexity that leads to difficulty. It isn't the complexity that raises problems. There is a lot of complexity in the world. The world is complex. That complexity is beautiful. I love trying to understand how things work. But that's because there's something to be learned from mastering that complexity.

Original: Chi proviene dall'inferno trova facilmente la soluzione a molte difficoltà.
Source: prevale.net

Lorentz (1991) " A scientist by choice". Speech by acceptance of the Kyoto Prize in 1991, cited in: Kerry Emanuel (2009) [http://www.nasonline.org/publications/biographical-memoirs/memoir-pdfs/lorenz-edward.pdf Edward Norton Lorenz 1917-2008 http://eaps4.mit.edu/research/Lorenz/Miscellaneous/Scientist_by_Choice.pdf. National Academy of Sciences Biographical Memoir.

Written statement (June 1919), as quoted in Time magazine (24 July 2006)
Context: Everybody sees a difficulty in the question of relations between Arabs and Jews. But not everybody sees that there is no solution to this question. No solution! There is a gulf, and nothing can bridge it… We, as a nation, want this country to be ours; the Arabs, as a nation, want this country to be theirs.

Death in the Clouds (1935)