 Like one of the founders of the School of Oxford Calculators—Richard Kilvington– Heytesbury takes Ockham’s nominalist position and affirms that the real physical world consists only of res absolutae, i.e., substances and qualities. They both acknowledge that terms such as “point”, “line”, “latitude”, and “degree” do not have any representation in reality, but are useful for describing different types of change. They also hold that time is not real since time is not distinguished realiter from the motion of celestial spheres, and motion is not distinguished realiter from the body which moves. Thus, they both contrast things that are really distinct with things distinguishable only in reason, i.e., in the imagination. Heytesbury follows Kilvington’s frequent use of the phrase secundum imaginationem to describe hypothetical situations in which the elements of the description, and not the situation itself, are of primary concern. The only requirement for an imaginable case is that it should not involve a formal logical contradiction; whether it is physically possible or not is a matter of indifference. As Wilson says,