FOR GALILEAN natural science, mathematical-physical nature is objective-true nature; it is this nature that is supposed to manifest itself in the merely subjective appearances. It is thus clear – and we have already pointed this out – that nature, in exact natural science, is not the actually experienced nature, that of the life-world. It is an idea that has arisen out of idealisation and has been hypothetically substituted for actually intuited nature. [Cf. § 36.] The conceptual method of idealisation is the fundament of the whole method of natural science (i.e., of the pure science of bodies ), the latter being the method of inventing “exact” theories and formulae and also of reapplying them within the praxis which takes place in the world of actual experience.
Edmund Husserl, The Crisis of European Sciences and Transcendental Phenomenology