Halliday & Matthiessen (1999: 66):
We have presented an initial sketch of the ideation base as a resource for construing our experience of the world around us and inside us. The focus of this sketch was the most general system of semantic types such as 'figure', 'being-&-having', 'participant', 'conscious being'. These semantic types are categories to which phenomenological instances are ascribed; they thus embody the fundamental principle of generalising across individual phenomenological variation. And they are located somewhere in delicacy between the most general type, the all-inclusive class of 'phenomenon', and the most delicate types we can recognise as being codified lexically in English.