are kinds void of essence, e.g. the kinds, Essence, Redness, Benevolence, Solidity, and the kind, Vertebrata, of which the essence is concrete. Essence is that which, by its resemblances and differences, determines the general place of a thing-its place in the system of kinds. Subject and essence may be identical, e.g. redness is its own essence. Essence may be concrete, e.g. a spine is the essence of an individual of the kind, Vertebrata. Accident is attribute that does not determine the general place of its subject, e.g. this or that thought or emotion, or the state of health or illness, is an attribute that does not determine the general place of the subject. The existence of the material orb known as Mars does not depend on its motion around the sun; the motion therefore is an accident of the orb: but it is a part of the essence of the planet, Mars, for regular motion around a sun is essential to a planet. The being projected or having been projected is, relatively to the projected body, an accident, but it is part of the essence of a projectile. To possess medical skill is an accident of the possessor quâ man, but it is part of the essence of the physician. These examples expose an ambiguity of the term Subject which tends to envelope our ideas of essence and accident in some confusion. To prevent confusion, it needs only that what is denoted by the term Subject be carefully distinguished, mindful that what is essence relatively to a given thing may be accident relatively to a part of the thing; e.g. revolution around a sun is essential to the planet, Mars, whereas it is a mere accident of the orb, Mars, which is but a part of the planet. The acuteness of an acute angle is the essence of the angle quá acute, and an accident of the angle quâ mere angle.

2. Essence is either natural or factitious, important or unimportant. The essences of organised things are examples of natural essence; those of the kinds, houses, and physicians, of factitious essence. The seventysevenths of solids, men born on Friday, the cows in John's field, are examples of kinds of which the essences are unimportant.

3. Attributes are either essential or accidental. Those on which the existence of the subject depends are essential; all others are accidental. Revolution around the sun is an essential attribute of the planet, Mars, and an accidental attribute of the orb, Mars. The life of a man is an essential quality; his visual faculty an accidental one.

4. Quantity is a species of quality. It is common and convenient to treat of quantity as though it were the opposite of quality, and for the sake of convenience we shall continue to do so. Custom sanctions the employment of the generic name of a thing as connoting privation of the differentia of some species of the genus to which the name refers, for example, in the depreciatory assertion "he is an animal," or "she is a mere female," or in the contrast of "ideas" and "things," or that of "words" and "acts," whereas words are acts and ideas are things. By nominally opposing Quantity to Quality we merely oppose it to all other qualities.

5. Let the term, Protean quality, denote an accident the specific like of which is a condition sine qua non of the existence of the subject, e.g. the figure of a piece of wax, and let a kind of such accidents, e.g. the kind, figure,

be termed a Protean kind. The existence of a piece of wax depends upon the Protean kind, Figure, but not upon any individual of the kind. I term the kind Protean on the metaphorical pretext that an abstract figure underlies every particular figure, as the Realists supposed an abstract Man to be the basis of every concrete man and to be one and the same in all concrete men,-one and the same variously metamorphosed. Note that the substitution of one Protean quality for another of the same kind in a concrete, e.g. the substitution of a square form for a round one in a piece of wax, does not affect the temporal identity or duration of the concrete. The temporal identity of a concrete is determined by the temporal identities of its qualities that are not Protean. The importance of this observation will appear when we treat of Sub

stance.

LXI.

A Change is a temporal beginning or end or a series of such beginnings and ends. It is either natural or supernatural. Natural change is either optional or unoptional. The beginning and end of a volition constitute an optional change; all other change is unoptional. An unoptional change is a beginning or end, or a beginning and end, of something naturally generable and annihilable, involving a metamorphosis of something not naturally generable and annihilable, the latter being divested of one naturally generable and annihilable attribute and clothed with another, e.g. the naturally ungenerable constituent of water divested of liquidity and clothed with hardness or

meta

aeriformity. By the way, unoptional or morphic change supposes that what changes remains the same. Supernatural change is a beginning or an end not naturally caused, e.g. a creation. An event is either a change or a beginning, an end and an intervening duration, e.g. the beginning, duration, and end of Cæsar.

LXII.

1. A relation supposes two or more things; the relation of a thing in one state or circumstance to itself in another is not an exception. For example, the relation of resemblance between the Bismarck of yesterday and the Bismarck of to-day supposes the two different circumstances yesterday and to-day. Identity may appear to be a relation and an instance of a relation that does not suppose two or more things. But identity is not a relation. It is compounded with a relation on which the discernment of it depends, and so is mistaken for a relation. That with which it is confounded is the relation of two or more aspects of a single remote object, e.g. that of Bismarck existent yesterday and that of Bismarck existent to-day, to the single enduring object Bismarck; or that of the aspect "four" and that of the aspect "two pairs" to the same real sum; or that of the aspect "acclivity" and that of the aspect "declivity" to the same incline; or that of the aspect "sum of the parts" and the aspect "whole" to the same complement of parts.

2. Relation is either extrinsic or intrinsic. Con

sidered in respect of the things related a relation is extrinsic, e.g. the fraternity of two brothers is extrinsic to each of them; considered in respect of a subject of which it is a constituent, a subject that is not one of the things related, e.g. the mutual relation of any two qualities of the same concrete qua constituent of the concrete, a relation is intrinsic. A given relation may be extrinsic in respect of one subject and intrinsic in respect of another. Extrinsicality distinguishes extrinsic relations from qualities, but intrinsic relations being constituents of their subjects, their difference from quality is as remote from saliency as the difference between two primary colours.

LXIII.

1. We now revert to Substance. By a change of connotation we may annex to the term Substance a signification which it has always been tending to acquire. The thesis that the Universe is a series of Universes which either spring or are created out of nothing, and either naturally return to nothing or are supernaturally annihilated, could not be seriously entertained by a sane mind. We are constrained to believe in the duration or temporal identity of the Universe, or rather of a concrete part of it. But parts of it are of comparatively brief duration, e.g. the forms we impose on wax, the liquidity which the atoms or molecules of melting ice assume, the aeriformity which

1 Duration is coincidence of the same with a divisible part of time or with all time. An instant is an indivisible part of time,—a mere limit of a part of time.