For Einstein, scientific theories were seen as the free creations of the human mind which we used to explain the world - but for Maturana, what needs explaining is precisely this "free creation of the human mind", i.e. the way in which the observer brings forth his world. Thus, central to Maturana's theory is the ontology of the observer. "Languaging takes place in the happening of living of the observer. To explain languaging, I must explain the living of the observer". Languaging is therefore Maturana's instrument for explanation and also his central problem.