Acquiring Purity

''Since he was a son of his old age'' [Vayeishev 37:3]

The acronym of the word ''zekunim'' - זְקֻנִים - [old age] says the Baál HaTurim, alludes to the five orders of mishnayos that Yaakov taught Yosef:  Zera'im, Kodshim, Nashim, Yeshu'os [Nezikin] and Mo'ed.

On this comment by the Ba'al HaTurim, the Imrei Emes [R' Avraham Mordechai Alter of Gur] asked the obvious question: There is one more order of mishnayos that the Ba'al HaTurim ignores - Taharos [purity]. Why did Yaakov not teach Yosef Taharos?

Seder Taharos, answered the Rebbe, cannot be taught.  Purity can only be acquired after an individual strives and exerts himself to achieve it on his own.

Source: Rabbi Yisrael Bronstein