<P> Ashes are ceremonially placed on the heads of Christians on Ash Wednesday , either by being sprinkled over their heads or , in English - speaking countries , more often by being marked on their foreheads as a visible cross . The words ( based on Genesis 3 : 19 ) used traditionally to accompany this gesture are , `` Memento , homo , quia pulvis es , et in pulverem reverteris . '' ( `` Remember , man , that thou art dust , and to dust thou shalt return . '' ) This custom is credited to Pope Gregory I the Great ( c. 540 -- 604 ) . In the 1969 revision of the Roman Rite , an alternative formula ( based on Mark 1 : 15 ) was introduced and given first place `` Repent , and believe in the Gospel '' and the older formula was translated as `` Remember that you are dust , and to dust you shall return . '' The old formula , based on the words spoken to Adam and Eve after their sin , reminds worshippers of their sinfulness and mortality and thus , implicitly , of their need to repent in time . The newer formula makes explicit what was only implicit in the old . </P>
what 's with the ashes on ash wednesday
reminds worshippers of their sinfulness and mortality and thus , implicitly , of their need to repent in time