President of Uruguay (2010 - 2015). Mujica tells us about how our obsession with making and earning money to obtain more possessions is robbing us of that which can never be bought.
In 1990 astronomer Carl Sagan suggested to NASA that Voyager 1 turn its camera around as it sailed past the orbit of Saturn and take a picture of the Earth from a distance of six billion kilometers. That pale blue dot in the photo taken by the spacecraft poignantly shows how utterly insignificant we are in the solar system and, needless to say, in the universe. Sagan ruminates on the significance of our insignificance and gives us one of the most moving and poetic reflections on humanity's unending squabbles over pieces of that barely visible dot.
In this interview physicist and Nobel laureate Richard Feynman conveys the difficulty of explaining something to the point that we comprehend it. Even then, however, we could keep on asking and go into sort of an infinite regress about the concepts, ideas, words that the teacher or explainer uses.