On his mother's side, Hayek was second cousin to the philosopher Ludwig Wittgenstein. His mother often played with Wittgenstein's sisters, and had known Ludwig well. As a result of their family relationship, Hayek became one of the first to read Wittgenstein's Tractatus Logico-Philosophicus when the book was published in its original German edition in 1921. Although Hayek met Wittgenstein on only a few occasions, Hayek said that Wittgenstein's philosophy and methods of analysis had a profound influence on his own life and thought. In his later years, Hayek recalled a discussion of philosophy with Wittgenstein, when both were officers during World War I. After Wittgenstein's death, Hayek had intended to write a biography of Wittgenstein and worked on collecting family materials; and he later assisted biographers of Wittgenstein.
Who was among the first readers of Ludwig Wittgenstein's book?
Hayek

Having sold more than 300 million records worldwide, Madonna is recognized as the best-selling female recording artist of all time by Guinness World Records. The Recording Industry Association of America (RIAA) listed her as the best-selling female rock artist of the 20th century and the second best-selling female artist in the United States, with 64.5 million certified albums. According to Billboard, Madonna is the highest-grossing solo touring artist of all time, earning US $1.31 billion from her concerts since 1990. She was ranked at number two, behind only The Beatles, on the Billboard Hot 100 All-Time Top Artists, making her the most successful solo artist in the history of American singles chart. Madonna became one of the five founding members of the UK Music Hall of Fame and was inducted into the Rock and Roll Hall of Fame in her first year of eligibility.
Since 1990, how much did Madonna make in her concerts?
$1.31 billion

A week after the implementation of the no-fly zone, NATO announced that it would be enforced. On 30 April a NATO airstrike killed Gaddafi's sixth son and three of his grandsons in Tripoli, though Gaddafi and his wife were unharmed. Western officials remained divided over whether Gaddafi was a legitimate military target under the U.N. Security Council resolution. U.S. Secretary of Defense Robert Gates said that NATO was "not targeting Gaddafi specifically" but that his command-and-control facilities were legitimate targetsincluding a facility inside his sprawling Tripoli compound that was hit with airstrikes on 25 April.
What city did NATO bomb on 25 April?
Tripoli