origins of words and phrases

origins of words and phrases:
"rule of thumb -No, this phrase is definitely NOT 'P.C'! Who knew? 'Rule of thumb' derived from the days when woman were sometimes beaten with a switch. To be 'kind' the switch could not be thicker than a thumb's width. This was made law in 1782 when an English judge stated that men were allowed to beat their wives but that the stick could not be thicker than one's thumb."