the problem which has to be solved; for every rival reading is a fact which has to be accounted for, and no acceptance of any one reading as original can be satisfactory which leaves any other variant incapable of being traced to some known cause or causes of variation. If a variation is binary, as it may be called, consisting of two variants, a and b, the problem for Transcriptional Probability to decide is whether it is easier to derive b from a, through causes of corruption known to exist elsewhere, on the hypothesis that a is original, or to derive a from b through similar agencies, on the hypothesis that b is original. If the variants are more numerous, making a ternary or yet more composite variation, each in its turn must be assumed as a hypothetical original, and an endeavour made to deduce from it all the others, either independently or consecutively; after which the relative facilities of the several experimental deductions must be compared together.
30. Hence the basis on which Transcriptional Probability rests consists of generalisations as to the causes of corruption incident to the process of transcription. A few of the broadest generalisations of this kind, singling out observed proclivities of average copyists, make up the bulk of what are not very happily called 'canons of criticism'. Many causes of corruption are independent of age and language, and their prevalence may be easily verified by a careful observer every day; while others are largely modified, or even brought into existence, by peculiar circumstances of the writings themselves, or of the conditions of their transmission. There is always an abundance of variations in which no practised scholar can possibly doubt which is the original reading, and which must therefore be derivative;
