It is on Maundy Thursday that in the Church of Rome the sacred oil is blessed, and the chrism prepared according to an elaborate ritual which is given in the Pontificale.
These crosses must have been anointed by the bishop with chrism in the ritual of consecration before the altar can be used.
In churches of the Greek rite a little of the old year's chrism is left in the jar to communicate its sanctity to that of the new.
Indeed the two states may contradict each other, as in the case of the 4th-century Christian pilgrim to Jerusalem who boasted that she had not washed her face for eighteen years for fear of removing therefrom the holy chrism of baptism.
Thus baptism is not valid if wine or ice be used instead of water, nor the Eucharist if water be consecrated in place of wine, nor confirmation unless the chrism has been blessed by a bishop; also olive oil must be used.
Such use of the chrism can be traced from the 2nd century.