r' tzadok hakohein on the tochacha

The Ramban writes in Parshas Bechukosai that the two parshiyos of tochacha in the Torah correspond to the destruction of the first and second Bais HaMikdash. (For the record: see the Abarbanel in P’ Ki Tavo who takes issue with this approach and says that there was never a true geulah from the first churban, just a temporary reprieve with very limited autonomy. We are still, according to Abarbanel, in galus from the destruction of the first Bais haMikdash, and both parshiyos of tochacha provide perspective on that event only). This view is echoed by the Zohar and many other Rishonim as well. R’ Tzadok HaKohein (Pri Tzadik, Ki Tavo) explains that the theme of each tochacha corresponds to the holiday which it precedes. Based on the takana of Ezra, Parshas Bechukosai is read before the holiday of Shavuos. “Al mah avdah ha’aretz”, wonders the Navi – what caused the destruction of the first Bais HaMikdash? Chazal tell us that the churban was a result of not saying birchas hatorah, a lack of appreciation and respect for the torah, which led to the other sins and churban. Therefore, this parsha of tochacha is read before the holiday of Shavuos, zman matan toraseinu. The second Bais haMikdash was destroyed because of the sin of sinas chinam, hatred and lack of unity. Therefore, the tochacha of Ki Tavo is read before Rosh haShana, when we daven “v’yei’asu kulam agudah achas l’asos retzoncha’, that the world should be united in its acceptance of the malchus of Hashem. See the Pri Tzadik for other parallels between the themes.