ויעש את הכיור נחשת…במראת הצבאת (ויקהל לח:ח)

Every person must study others as if looking into a mirror. Just as a mirror reflects one’s own flaws, so too, when we observe another’s shortcomings, we should see them within ourselves and learn how to correct them. As the Mishna (אבות ד:א)
teaches: “איזהו חכם הלומד מכל אדם” — Who is wise? One who learns from every person.
Similarly, when the Kohanim washed before performing the service, they had to cleanse themselves from every imperfection or blemish. The כיור (basin) in which they washed was made of mirrors, serving as a reminder to recognize one’s own shortcomings through the reflection of others. For it is often difficult to see our own flaws directly—yet, by observing them in another, the mirror helps us identify and correct them.