Halliday & Matthiessen (1999: 188):
We were able to define a thing by reference to one particular role within a figure: namely, as Carrier in an ascriptive figure construed grammatically as Carrier + Process + Attribute. But it is characteristic of things that they can take on a variety of roles in figures of all kinds. Here is a set of examples to illustrate this functional range:
Here we find one and the same class of thing functioning(a) as Actor, as Goal, and as Beneficiary in a material process;(b) as Phenomenon in a mental process;(c) as Sayer, as Verbiage, and as Target in a verbal process;(d) as Carrier, as Token, and as Value in a relational process, and(e) as Minirange in a circumstance of Location.
Even if we generalise across these configurational types in ergative terms, these examples still cover the full participant spectrum: the 'book' occurs as Medium, as Agent, as Beneficiary and as Range.