Halliday & Matthiessen (1999: 209):
The former [closed grammatical systems] are taxonomically simple (although they are notoriously difficult to interpret in lexical glosses); they include specific/non-specific; personal/demonstrative; near/far; total/partial &c. In contrast, elements at the latter end [open lexical sets] tend to be construed in complex taxonomies. That is, greater experiential complexity is handled by means of greater taxonomic complexity. […] Qualities lie at different places along these various dimensions; hence they vary in their potential for taking on rôles in different types of figure.