In *[A Plea for Captain John Brown][1]*, Thoreau writes: 

>I have no respect for the penetration of any man who can read the report of that conversation, 
and still call the principal in it insane. It has the ring of a saner sanity than an ordinary 
discipline and habits of life, than an ordinary organization, **secure**. 

The comma after *organization* makes me think that *secure* is used a noun here but I'm not sure of that as [I have not read anywhere][2] that *secure* 
is used as a noun.
On the other hand, the lack [parallelism][3], in the form of *than*, makes me consider reading this sentence like so: *It has the ring of a saner sanity than an ordinary 
discipline and habits of life, than an ordinary, **secure** organization.*

 Is the word used here as a noun?
What does *secure* mean here?

[1]: https://www.gutenberg.org/cache/epub/2567/pg2567-images.html
[2]: https://en.wiktionary.org/wiki/secure
[3]: https://en.wikipedia.org/wiki/Parallelism_(grammar)