Purity and Paschal Sacrifice
"And there was the case of Yosef the Cohen, whose wife died on Pesach eve, and he didn't want to defile himself [by burying her, because then he would be unable to participate in the Pesach, the Paschal sacrifice]. His brother priests ganged up on him and defiled him against his will" (Zebahim 100a).
This is one of several stories in which Hazal reveal their discomfort with placing disproportionate emphasis on purity and sacrifice. They are important, and two entire orders of the Mishna and Tosefta are devoted to such matters. But people have a tendency to put ritual before more basic concerns.
Steven Fraade, for one, has shown how Hazal translated the Biblical emphasis on priesthood and the Temple as the center of Jewish religious life, into a worldview focused on learning as the ideal and Sages as the national leaders. For instance, Deuteronomy 17, 9 makes it clear that the supreme court consists of Kohanim. The Sifre ad loc learns from here, slightly disingenuously, that it is preferable, though by no means crucial, that the court include Kohanim among the judges. For Hazal, the idea of the Kohen as God's intermediary with His people has been inherited by the Sages.
Today I came across a similar migration of concepts. Victor Aptowitzer (famous for publishing Sefer Ra'avya) pointed out that, in the writings of early French and German rabbis, terminology of purity and impurity is applied regularly to what's known as Issur ve'Heter. Certain foods are forbidden by Halacha under certain circumstances. But they do not cause impurity. These Rishonim blurred that distinction. Instead of saying that the wine of non-Jews is forbidden for drinking, they would say it was impure. [Avigdor Aptowitzer, Studies in the Literature of the Geonim, Jerusalem 1941, p. 62 (Hebrew)]
I guess this kind of ties in to my previous posting. We don't have a Temple, and purity is a concept that is not immediately relevant. One response to that would be to say that it is irrelevant, and good riddance.
Another would be to try and bring those concepts back as soon as possible.
But a third is to find other avenues along which to make these concepts relevant.