Kitap 5
7.2
Further there is always a certain tacit prejudice against documentary evidence, since no one can be forced to give such evidence save of his own free will, whereby he shows that he harbours unfriendly feelings towards the person against whom he bears witness. On the other hand an advocate should be chary of denying that a friend may give true evidence against a friend or an enemy against an enemy, provided they are persons of unimpeachable credit. But the subject admits of copious discussion, from whichever side it be regarded.
7.3
The task of dealing with the evidence of witnesses present in court is, however, one of great difficulty, and consequently whether defending or impugning them the orator employs a twofold armoury in the shape of a set speech and examination. Interrogatio includes both the examination in chief and cross-examination. In set speeches it is usual to begin with observations either on behalf of or against witnesses in general.
7.4
In so doing we introduce a commonplace, since one side will contend that there can be no stronger proof than that which rests on human knowledge, while the other, in order to detract from their credibility, will enumerate all the methods by which false evidence is usually given.
