Upon entering the Kodesh Hakadoshim, Holy of Holies, the Kohen Gadol divested himself of his ornate priestly vestments and clothed himself in simple, white linen. In public, the Kohen was responsible to maintain the dignity appropriate to his noble station in life. When he went into the Holy of Holies to confess the sins of Am Yisrael, to entreat Hashem on behalf of His people, he entered dressed as an ordinary Kohen. At the spiritually heightened moment, the most solemn of the year, the most venerated of men became a simple mortal. The facades of dignity and station in life no longer distinguished him from any other person. This was his moment of truth. All human devices are valueless when man comes in face-to-face confrontation with his maker. This awesome feeling affected the Kohen Gadol’s entire being, mirrored in his external clothing.
These “sacred” vestments are worn by each Jew as he is placed in his “final” resting place. The body is clothed in white linen shrouds in preparation for the ultimate day of judgment. Before Hashem, all men are the same. The only distinguishing characteristics are the merits of Torah study and mitzvah performance which an individual has accrued during his lifetime.