The term _mode_ has a variety of meanings, some very wide, some restricted. When one concept determines or limits another in any way we may call it a mode of the latter. If there is no real distinction between the determining and the determined thought-object, the mode is called a _metaphysical_ mode: as rationality is of animality in man. Again, created things are all “modes” of being; and the various aspects of a creature may be called “modes” of the latter: as “finiteness” is a mode of every created being. We do not use the term in those wide senses in the present context. Here we understand by a mode some positive reality which so affects another and distinct reality as to determine the latter proximately to some definite way of existing or acting, to which the latter is itself indifferent; without, however, adding to the latter any new and proper entity other than the said determination.(264) Such modes are called _physical_ modes. And some philosophers maintain that there are not only _accidental_ modes, thus really distinct from the substance, but that there are even some _substantial_ modes really distinct from the essence of the substance which they affect: for instance, that the really distinct constitutive principles of any individual corporeal substance, matter and form, are actually united only in virtue of a substantial mode whereby each is ordained for union with the other; or that _subsistence_, whereby the individual substance is made a subsistent and incommunicable “person” or “thing,” is a substantial mode of the individual nature.(265) With these latter we are not concerned here, but only with accidental modes, such as external shape or figure, local motion, position, action,(266) etc. Now when a substance is affected by such accidents as these it is impossible on the one hand to maintain that they add any new positive entity of their own to it; they do not seem to have any reality over and above the determination or modification in which their very presence in the substance consists. And on the other hand it cannot be denied that they express some real predicate which can be affirmed of the substance in virtue of their presence in it, and that independently of our thought; in other words it cannot be maintained that they are mere figments or forms of thought, mere _entia rationis_. If a piece of wax has a certain definite shape, this shape is inseparable from the wax: it is nothing except in the wax, for it cannot exist apart from the wax; but in the wax it is something in some real sense distinct from the wax, inasmuch as the wax would persist even if it disappeared. No doubt it is essential to the wax, as extended in space, to have some shape or other; but it is indifferent to any particular shape, and hence something distinct from it is required to remove this indifference. This something is the particular shape it actually possesses. The shape, therefore, is an accidental mode