  We show that inflation with a quadratic potential occurs naturally in
theories where an axion-like field mixes with a 4-form. Such an axion is
massive, with the mass which arises from the mixing being protected by the
axion shift symmetry. The 4-form backgrounds break this symmetry spontaneously
and comprise a mini-landscape, where their fluxes can change by emission of
membranes. Inflation can begin when the 4-form dominates the energy density.
Eventually this energy is reduced by membrane emission and the axion can roll
slowly towards its minimum, as in the simplest version of chaotic inflation.
