[Avodah] Seeking source: Rav Hirsch on the Churban

[Joel C. Salomon]

I recall recently reading something by Rav Hirsch where he says that the
mourning on Tisha B'Av is not so much on the destruction of the Beis
Hamikdosh, but that it had to be destroyed.  This tied in to Rav
Hirsch's take on Am Yisroel as the "mamleches kohanim" to the world.

I had thought this was in his essay on Chazon Yeshayahu (in the
Collected Writings, volume IV), but I do not see this concept there.
Does anyone know where I can find it?

Thank you,
--Chesky