Conversation so far:
What is meant by secular nature?
By the time of Horace Mann's leadership in education, various developments fostered a secular school system with a religiously passive stance.
What are some important aspects of secular nature?
Horace Mann stated that this position resulted in a near-universal use of the Bible in the schools of Massachusetts.
Was Horace Mann well known to a lot of people?
Horace Mann worked with a remarkable intensity, holding teachers' conventions, delivering numerous lectures and addresses, carrying on an extensive correspondence, and introducing numerous reforms.

Question: What else did he do regarding the secular nature?
Self-contained rewrite: What else did Horace Mann do regarding the secular nature?