- Ralph Waldo Emerson (Wikipedia)
Ralph Waldo Emerson (May 25, 1803 – April 27, 1882), who went by his middle name Waldo, was an American essayist, lecturer, philosopher, abolitionist and poet who led the transcendentalist movement of the mid-19th century. He was seen as a champion of individualism and critical thinking, as well as a prescient critic of the countervailing pressures of society and conformity. Friedrich Nietzsche considered him “the most gifted of the Americans”, and Walt Whitman referred to him as his “master”.
- Barber paradox (Wikipedia)
The barber paradox is a puzzle derived from Russell’s paradox. It was used by Bertrand Russell as an illustration of the paradox, though he attributes it to an unnamed person who suggested it to him. The puzzle shows that an apparently plausible scenario is logically impossible. Specifically, it describes a barber who is defined such that he both shaves himself and does not shave himself, which implies that no such barber exists.