While Structural Linguists advance towards a hermetic theory of language, Althusser proposes, even more strangely, a hermetic theory of science. Unlike science as we ordinarily conceive it, Althusser's Science does not stoop to grubbing around for evidence amongst the things of the outside world, but constitutes itself out of virtually nothing but a pure process of thought. This is a Science on the level of Hegel's Science or Spinoza's scientia intuitiva – a level from which one looks down upon the limited knowledges that natural scientists produce. This is a Science for philosophers.