Blind Leading The Blind Meaning

Example :   Grandma teaching you to drive is like the blind leading the blind.1843, James Fenimore Cooper, Wyandotte, ch. 5:  "The Lord preserve us from evil times. . . . Without his grace, we are the blind leading the blind."1896, Amelia E. Barr, A Knight of the Nets, ch. 2:  "I have been giving them some good advice."  "Good advice!" laughed Janet. "Between you and Jamie Logan, it is the blind leading the blind, and nothing better."1995 March 1, John F. Dickerson, "Aging: Never Too Old," Time (retrieved Aug 2014):  Instructor George Breathitt asked an audience of 300 computer enthusiasts in Louisville, Kentucky, how many seniors in the group would like to teach other seniors about computers. A younger member of the audience quipped disdainfully, "Wouldn't that be the blind leading the blind?"