Now a creed is at once the broadest and the narrowest thing in the world. In its nature it is as broad as its scheme for a brotherhood of all men. In its nature it is limited by its definition of the nature of all men. This was true of the Christian Church, which was truly said to exclude neither Jew nor Greek, but which did definitely substitute something else for Jewish religion or Greek philosophy. It was truly said to be a net drawing in of all kinds; but a net of a certain pattern, the pattern of Peter the Fisherman.  [...] Now in a much vaguer and more evolutionary fashion, there is something of the same idea at the back of the great American experiment; the experiment of a democracy of diverse races which has been compared to a melting-pot. But even that metaphor implies that the pot itself is of a certain shape and a certain substance; a pretty solid substance. The melting-pot must not melt. The original shape was traced on the lines of Jeffersonian democracy; and it will remain in that shape until it becomes shapeless. America invites all men to become citizens; but it implies the dogma that there is such a thing as citizenship.

-What I Saw in America (1922)