Halliday & Matthiessen (1999: 546-7):
In the world of classical physics, the flux of experience was held under control: reality had to be prevented from wriggling, while it could be observed and experimented with. The control over experience is partly a physical matter; but it is also in part semiotic, and the semiotic control of experience is achieved by the nominalising power of the grammar. Since it is the grammar that has construed it in the first place, the grammar is able to transform it by reconstruing it in other terms. Grammatical metaphor played an important role in shaping our humanist world.
But it shaped it in a way which soon came to be felt as decidedly inhuman. Already at the end of the eighteenth century, within a hundred years of Newton's "Opticks", people were reacting against the rigidity of the world of physics; what they could not accept were the ideological constraints set up by scientific discourse, by a grammar which construed all experience in terms of things. In our own twentieth century the scientists themselves have become weary of it, finding that it prevents them from engaging with the indeterminacy and the flow that they now regard as fundamental — let alone with the concept of the universe as conscious and communicating, as something itself to be interpreted as a semiotic system-&>process. Once we conceive of reality in semiotic terms, it can no longer surprise us that language has the power to construe it, maintain it, and transform it into something else.