An Etymological Dictionary of the German Language/Annotated/Einfalt
Einfalt, feminine, ‘simplicity, silliness,’ from Middle High German einvalt, einvalte (-vęlte), feminine, Old High German einfaltî, feminine, ‘simplicity, silliness’; compare Gothic ainfalþei, feminine, ‘silliness, good nature’ — an abstract noun from Gothic ainfalþs, ‘silly,’ Old High German and Middle High German einfalt, ‘silly,’ whence Old High German einfaltîg, Middle High German einveltec, adjective, ‘silly.’ See falt. —