2. In like manner an invariable concomitance is ascertained by the ascertainment of identity (_e.g._, a sisu-tree is a tree, or wherever we observe the attributes of a sisu we observe also the attribute arboreity), an absurdity attaching to the contrary opinion, inasmuch as if a sisu-tree should lose its arboreity it would lose its own self. But, on the other hand, where there exists no absurdity, and where a (mere) concomitance is again and again observed, who can exclude all doubt of failure in the concomitance? An ascertainment of the identity of sisu and tree is competent in virtue of the reference to the same object (_i.e._, predication),--This tree is a sisu. For reference to the same object (predication) is not competent where there is no difference whatever (_e.g._, to say, "A jar is a jar," is no combination of diverse attributes in a common subject), because the two terms cannot, as being synonymous, be simultaneously employed; nor can reference to the same object take place where there is a reciprocal exclusion (of the two terms), inasmuch as we never find, for instance, horse and cow predicated the one of the other. It has thus been evinced that an effect or a self-same supposes a cause or a self-same (as invariable concomitants). If a man does not allow that inference is a form of evidence, _pramáṇa_, one may reply: You merely assert thus much, that inference is not a form of evidence: do you allege no proof of this, or do you allege any? The former alternative is not allowable according to the maxim that bare assertion is no proof of the matter asserted. Nor is the latter alternative any better, for if while you assert that inference is no form of evidence, you produce some truncated argument (to prove, _i.e._, infer, that it is none), you will be involved in an absurdity, just as if you asserted your own mother to be barren. Besides, when you affirm that the establishment of a form of evidence and of the corresponding fallacious evidence results from their homogeneity, you yourself admit induction by identity. Again, when you affirm that the dissentiency of others is known by the symbolism of words, you yourself allow induction by causality. When you deny the existence of any object on the ground of its not being perceived, you yourself admit an inference of which non-perception is the middle term. Conformably it has been said by Tathágata-- "The admission of a form of evidence in general results from its being present to the understanding of others. "The existence of a form of evidence also follows from its negation by a certain person." All this has been fully handled by great authorities; and we desist for fear of an undue enlargement of our treatise.