Symbols themselves have lost much of their power to reverberate in the mind and feeling since this power depends on the existence of a coherent world. Without such a world symbols tend to become indistinguishable from signs. (117)
How is Tuan differentiating between sign and symbol? It seems that he sees symbols as meaningful in and of themselves even as they indicate something else, whereas signs can only indicate something else. Or, perhaps in religious terms, symbols participate in the qualities of what they point toward, whereas signs may not. Symbols belong to a set of other symbols in a relatively closed (coherent) system; signs can exist outside such a system.