Foundations as Superstructure. (Reflections of a practicing   mathematician)
  This talk presents foundations of mathematics as a historically variable set of principles appealing to various modes of human intuition and devoid of any prescriptive/prohibitive power. At each turn of history, foundations crystallize the accepted norms of interpersonal and intergenerational transfer and justification of mathematical knowledge. 
Yuri I. Manin
math.HO