Plena are the characteristic properties of material thing, of the
thing we perceive in our daily experience. According to Husserl,
the attempt to explain their features into the language of Physics
is the core of the modern science of nature. Colours and smells
are not directly reducible to geometrical forms and algebraic functions.
In order to explain natural processes using mathematical
terms, scientists need to find out how it is possible to measure
them. Galileo claims that the world is made up of mathematical
formulae, Husserl instead tries to understand the limits of the
validity of this claim. In order to do this, the role of subjective
experience must be taken into account.