A necessity that can be met by nothing less than the blood of Jesus

"The emphasis in these passages [Hebrews 1:1-3; 2:9-18; 9:9-14; 22-28] rests upon the finality, perfection, and transcendent efficacy of Christ's sacrifice. Such finality, perfection, and efficacy are necessitated by the gravity of sin, and sin must be effectively removed if salvation is to be realized. It is this consideration that gives such strength to the necessity, spoken of in 9:23, to the effect that while the patterns of the things in the heavenlies should be purified with the blood of goats and calves, the heavenly things themselves should be purified by the blood of none other than the Son. In other words, there is stated to be a necessity that can be met by nothing less than the blood of Jesus. But the blood of Jesus is blood that has the requisite efficacy and virtue only by reason of the fact that he who is the Son, the effulgence of the Father's glory and the express image of his substance, became himself also partaker of flesh and blood and thus was able by one sacrifice to perfect all those who are sanctified. It is surely not an unwarranted inference to conclude that the thought here presented is that only such a person, offering such a sacrifice, could have dealt with sin so as to remove it and could have made such purification as would secure for the many sons to be brought to glory access into the very holiest of the divine presence."

John Murray, Redemption Accomplished and Applied, pg. 14.