Halliday (2008: 166):
Written languages evolved to their present state in the “modern” period beginning with the European “renaissance”; but they were already launched along that journey in the ancient written cultures of Greece and Rome, India and China. The science and technology of the ancient world already needed virtual entities to think with, elements like motion and heat and distance and sum and addition which are the supports of the primary phase of our modern education. The more highly theorised learning of the renaissance took this metaphoric strategy one step further, constructing complex syndromes of virtual entities, virtual qualities and classes and virtual processes to achieve the “favourite clause type” of scientific writing — and now of many other kinds of writing besides the scientific.