The rite of purifying with the ashes of the red heifer was one of the most familiar and impressive of the Mosaic institutions. That its observance was maintained through the whole course of Israel’s history, is evinced by the frequent allusions of the sacred writers. King Saul found in the ordinances on this subject an explanation of David’s absence from his table.—“Something hath befallen him. He is not clean: surely he is not clean.”—1 Sam. xx, 26. The words of David himself have been referred to already, as he cries,—“Purge me with hyssop, and I shall be clean.”—Psa. li, 7. This was written about five hundred years after the giving of the law. Three centuries later, the Lord says to Israel by Hosea,—“Their sacrifices shall be unto them as the bread of mourners,” (that is, bread made or touched by those that were defiled by the dead), “all that eat thereof shall be polluted.”—Hosea ix, 4. Isaiah began his prophecy about twenty-five years later,—about B. C. 760-698. In his time a great revival took place, under the hand of King Hezekiah, in connection with which the laws of purification came into prominent notice. It began with the exhortation of Hezekiah, to the priests and Levites.—“Hear me, ye Levites; _sanctify_” (or, cleanse) “now yourselves, and sanctify the house of the Lord God of your fathers; and carry forth the filthiness out of the holy place.”—2 Chron. xxix, 5. When this was done, the king appointed a service of dedication. In it “the priests were too few, so that they could not flay all the burnt offerings; wherefore, their brethren the Levites did help them, till the work was ended, and until the other priests had sanctified themselves: for the Levites were more upright in heart to sanctify themselves than the priests.”—vs. 34. Immediately afterward the king kept a great passover, gathering the remnants of the ten tribes, with Judah. “And the priests and the Levites were ashamed and sanctified themselves, ... for there were many in the congregation that were not sanctified: therefore the Levites had charge of the killing of the passovers for every one that was not clean, to sanctify them unto the Lord. For a multitude of the people, even many of Ephraim and Manasseh, Issachar and Zebulun, had not cleansed themselves, yet did they eat the passover otherwise than it was written. But Hezekiah prayed for them, saying, The good Lord pardon every one that prepareth his heart to seek God, the Lord God of his fathers, though he be not cleansed according to the purification of the sanctuary. And the Lord hearkened to Hezekiah, and healed the people.”—Ib. xxx, 15-20.