Varṇa: The Four-Fold Order

Thirty lessons have described what Hindus hold, whom they address and what they do. Four times along the way the course has stopped at the same locked door — Lesson 3 on who was let into the chain of transmission, Lesson 13 on varṇa as a contested question, Lesson 18 on who the āśrama scheme is addressed to, Lesson 30 on temple entry — and four times it has said the question would be taken up later.

This is later.

The lexicon gives varṇa a long entry, and the order matters.