Ladislaus is trying to make multiple points, but one of them is that 'things of the body' are not evil. The devil tempts some souls to excessive piety, which can cause a detestation of the physical world. We are physical AND spiritual beings. We are not angels. The body should be subordinate to the spiritual but not replaced by the spiritual. The balance is to use the body in the service of God, which entails both natural and spiritual duties.