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the case; but that no single substance admits of varying degrees

within itself. For instance, one particular substance, 'man', cannot

be more or less man either than himself at some other time or than

some other man. One man cannot be more man than another, as that which

is white may be more or less white than some other white object, or as

that which is beautiful may be more or less beautiful than some

other beautiful object. The same quality, moreover, is said to subsist

in a thing in varying degrees at different times. A body, being white,

is said to be whiter at one time than it was before, or, being warm,

is said to be warmer or less warm than at some other time. But

substance is not said to be more or less that which it is: a man is

not more truly a man at one time than he was before, nor is

anything, if it is substance, more or less what it is. Substance,

then, does not admit of variation of degree.

The most distinctive mark of substance appears to be that, while

remaining numerically one and the same, it is capable of admitting

contrary qualities. From among things other than substance, we

should find ourselves unable to bring forward any which possessed this

mark. Thus, one and the same colour cannot be white and black. Nor can

the same one action be good and bad: this law holds good with

everything that is not substance. But one and the selfsame

substance, while retaining its identity, is yet capable of admitting

contrary qualities. The same individual person is at one time white,

at another black, at one time warm, at another cold, at one time good,

at another bad. This capacity is found nowhere else, though it might

be maintained that a statement or opinion was an exception to the

rule. The same statement, it is agreed, can be both true and false.

For if the statement 'he is sitting' is true, yet, when the person

in question has risen, the same statement will be false. The same

applies to opinions. For if any one thinks truly that a person is

sitting, yet, when that person has risen, this same opinion, if

still held, will be false. Yet although this exception may be allowed,