purifying = purification, i.e. pure blood as distinct from the other.
threescore and six days. Double that after a man child. See Lev_12:4 (14 + 66 = 80). This ordinance was not on account of any disparity between the sexes, but was in order to regulate them, so that the birth-rate of females might not be in too great excess, as it otherwise would have been, and is, where this ordinance is not known or observed.