Allan Kardec ( Hippolyte LÃ on Denizard Rivail October 3 , 1804 - March 31 , 1869 ) was a French philosopher and teacher . Allan Kardec is the pen name of the French teacher and educator Hippolyte LÃ on Denizard Rivail ( Lyon , October 3 , 1804 â `` Paris , March 31 , 1869 ) .