Giles Duncombe, Tryals per Pais1665
And first as to their [the Jury's] number twelve: and this number is no less esteemed by our law than by Holy Writ. If the twelve apostles on their twelve thrones must try us in our eternal state, good reason hath the law to appoint the number of twelve to try our temporal. The tribes of Israel were twelve, the patriarchs were twelve, and Solomon's officers were twelve. I Kings, IV, 7. . . . Therefore not only matters of fact were tried by twelve, but of ancient times twelve judges were to try matters in law, in the Exchequer Chamber, and there were twelve counsellors of state for matters of state; and he that wageth his law must have eleven others with him who believe he says true. And the law is so precise in this number of twelve, that if the trial be by more or less, it is a mistrial.
The Founders' Constitution
Volume 5, Amendment VII, Document 1
The University of Chicago Press
Easy to print version.