The high priest was required to change into special garments of simple linen in order to enter the Holy of Holies.
Becoming a New Person
וּפָשַׁט אֶת בִּגְדֵי הַבָּד אֲשֶׁר לָבַשׁ בְּבֹאוֹ אֶל הַקֹּדֶשׁ וְהִנִּיחָם שָׁם:
(ויקרא טז:כג)
[Aaron] must remove the linen garments that he wore when he entered the Holy [of Holies], and leave them [in the Tabernacle].
Leviticus 16:23
The linen garments worn by the high priest on Yom Kippur must never be worn again. The reason for this rule is that when a person repents sincerely, he or she is transformed into a new person. Inasmuch as the essence of Yom Kippur is repentance, the garments used by the high priest to perform the Yom Kippur rituals had to be new each year.1
It's good that once the learning and growth traits are there combined with the wisdom it becomes exciting to change for the better as everday a new aspect is learnt.