But this principle is true only when the added attribute is not merely the same verbally, but has the same significance in qualifying both terms.

We cannot argue _A mouse is an animal_; therefore, _A large mouse is a large animal_; for 'large' is an attribute relative to the normal magnitude of the thing described.
Sec.4.Conversion is Immediate Inference by transposing the terms of a given proposition without altering its quality.

If the quantity is also unaltered, the inference is called 'Simple Conversion'; but if the quantity is changed from universal to particular, it is called 'Conversion by limitation' or '_per accidens._' The given proposition is called the 'convertend'; that which is derived from it, the 'converse.' Departing from the usual order of exposition, I have taken up Conversion next to Subalternation, because it is generally thought to rest upon the principle of Identity, and because it seems to be a good method to exhaust the forms that come only under Identity before going on to those that involve Contradiction and Excluded Middle.

Some, indeed, dispute the claims of Conversion to illustrate the principle of Identity; and if the sufficient statement of that principle be 'A is A,' it may be a question how Conversion or any other mode of inference can be referred to it.

But if we state it as above (chap.vi.Sec.