Secure is a flat adverb (and a sentence adverb) here, meaning securely or assuredly. You can read the sentence as:
Assuredly, it has the ring of a saner sanity than an ordinary discipline and habits of life, than an ordinary organization.
You can derive this by looking at both an adjective and adverb definition of secure and the adverb definition of securely:
secure, adj., adv., and n.1
A. adj. II. That is certain; fully assured; (objectively) safe.
B. adv. In a secure manner; securely, safely; easily.securely, adv.
3. Without risk of error; with certainty.Source: Oxford English Dictionary (login required)
By the way, secure as a noun means secure people considered as a class, like the rich and the poor.
Answer from Tinfoil Hat on Stack ExchangeVideos
Secure is a flat adverb (and a sentence adverb) here, meaning securely or assuredly. You can read the sentence as:
Assuredly, it has the ring of a saner sanity than an ordinary discipline and habits of life, than an ordinary organization.
You can derive this by looking at both an adjective and adverb definition of secure and the adverb definition of securely:
secure, adj., adv., and n.1
A. adj. II. That is certain; fully assured; (objectively) safe.
B. adv. In a secure manner; securely, safely; easily.securely, adv.
3. Without risk of error; with certainty.Source: Oxford English Dictionary (login required)
By the way, secure as a noun means secure people considered as a class, like the rich and the poor.
The sanity referred to here is secure:
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.
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It has the ring of a sanity
saner than an ordinary discipline and habits of life,
saner than an ordinary organization,
secure.
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It has the ring of a secure sanity,
saner than an ordinary discipline and habits of life,
saner than an ordinary organization.
Left to the end for emphasis, and a contrast to the rather long comparative strings that come between it and sanity.
There is no reason to analyze it as a noun as it could not take any dependents typical of one such as determiners (no, a, my) or adjectives (good, sure, possible).