Nor can this be a sufficient ground for inferring, as the objection does, that in such a case the form would be distant from its matter as much as the sun is from the planets. The form, as such, cannot be considered as a term of the relation of distance; for, as we have already remarked, there is no distance without two formal ubications. Now, the form, as such, has no formal ubication, but is reduced to the predicament _ubi_ only by the ubication of its own matter. Hence it is impossible rationally to conceive a distance between the matter and its form, however great may be the sphere of activity of the material element. When the substantial form is regarded as a principle of accidental actions, we may indeed consider it, if not as composed of, at least as equivalent to, a continuous series of concentric spherical forms overlying one another throughout the whole range of activity; and we may thus conceive every one of them as _virtually_ distant from the material centre, its virtual distance being measured by its radius. But, strictly speaking, the radius measures the distance between the agent and the patient, not between the agent and its own power; and, on the other hand, as the imagined series of concentric sphericities continues uninterruptedly up to the very centre of the sphere, we can easily perceive that the substantial form, even as a principle of action, is immediately and intrinsically terminated to its own matter. _A third objection._—What conception can we form of an _indefinite_ sphere? For a sphere without a spherical surface is inconceivable. But an indefinite sphere is a sphere without a spherical surface; for if there were a surface, there would be a limit; and if there were a limit, the sphere would not extend indefinitely. It is therefore impossible to conceive an indefinite sphere of activity. This objection is easily answered. A sphere without a spherical _form_ is indeed inconceivable; but it is not necessary that the spherical form should be a _limiting_ surface, as the objection assumes. We may imagine an indefinite sphere of matter; that is, a body having a density continually decreasing in the inverse ratio of the squared distances from a central point. Its sphericity would consist in the spherical decrease of its density; which means that the body would be a sphere, not on account of an exterior spherical limit, but on account of its interior constitution. Now, what we say of an indefinite sphere of matter applies, by strict analogy, to an indefinite sphere of power. Only, in passing from the former to the latter, the word _density_ should be replaced by _intensity_; for intensity is to power what density is to matter. And thus an indefinite sphere of power may have its spherical character within itself without borrowing it from a limiting surface. We may, therefore, consider this third objection as solved.