"So, in practice, Western history has used two standards of evidence for transmission: one ultra-lax standard of evidence for transmission from "Greeks", and another ultra-strict standard for transmission to the West. For cases of alleged transmission from the Greeks, mere speculations—a speculative chronology combined with speculative attribution—are regarded as ample evidence of transmission. In the other direction, similarity with a real earlier work, by a real author, together with a clear channel of transmission, do not prove anything, for there is always the possibility of repeated miracles by which any number of people in the West may independently reinvent things just when they could be transmitted."