You accept color differences, affirm them, celebrate them, but don't allow them to become a barrier to human community, " said Baldwin, author of a new King book, "In A Single Garment of Destiny: A Global Vision of Justice.

NPR: King 'Content Of Character' Quote Inspires Debate

Simultaneously, the construction of sewage channels and the Gowanus Expressway on the community's eastern edge created a physical barrier between Red Hook and the rest of Brooklyn, crippling the already struggling community further.

BBC: A remote hook in New York��s harbour

As string theory involves intricate mathematics, the barrier to entry into its community is high.

ECONOMIST: Theoretical physics