A verse in some “Latin book in Gothic black letter” (usually Ps. li. 1), formerly set by the ordinary of a prison before a malefactor claiming benefit of clergy, in order to test his ability to read. If the ordinary or his deputy said “legit ut clericus” (he reads like a clerk or scholar), the malefactor was burned in the hand and set free, thus saving his neck.
ergo A verse or term on the pronunciation which an individual's fate depends; a shibboleth.