E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Forecasting future events by the Bible. The plan was to open the sacred volume at random, and lay your finger on a passage without looking at it. The text thus pointed out was supposed to be applicable to the person who pointed it out. (Greek, biblia, Bible; manteia, prophecy.) (See SORTES.)
Another process was to weigh a person suspected of magic against a Bible. If the Bible bore down the other scale, the accused was acquitted.