  The occupation number of a field is a sound discriminator between classical
and quantum regimes. In this pamphlet we give an overview of what we can learn
about inflationary magnetogenesis just by looking at the occupation numbers of
the classical magnetic fields observed today, and those of the quantum
electromagnetic field during inflation. The sole occupation number behaviour
dictates that for a pure Maxwell theory in de Sitter space it appears
impossible to match the two epochs.
