What I didn't know was that those steps -- leading to the lofty highlight of my Kumano Kodo pilgrimage -- would be on a 70-degree incline.

CNN: World's best unknown hike: Japan's Kumano Kodo

To be fair, country music's popularity has been on a steady incline for more than 20 years, Billboard country chart manager Wade Jessen says.

CNN: Obsessions: Crazy about country music

But, to judge from Mr Sabbagh's book, most mathematicians would incline more towards Hilbert's view that a solution will one day be found for even the most difficult mathematical problem.

ECONOMIST: Mathematics