Brass

Silver is the figure of purged character. Mal. 3:3; Isa. 1:22, 25)
Gold tried faith.
Brass represents Human flesh.

Outside the tabernacle brass was primarily used. The lavar of Brass, and the altar of brass.  

Once we make the commitment to try and put off the flesh, we enter through the door with 5 posts (which possibly ‎represented Paul, James, Peter, Jude, and John) and whose sockets were made of brass (Exo 36:38).

Then you are in the Holy Place, where instead of Brass, you see Golden altar of incense and Golden lampstand (tried faith).

The veil hung on 4 posts (Matthew, Mark, Luke, John), and their posts instead having sockets of brass, had silver.   Flesh is the problem and as we move through the tabernacle from the world to immortality, the problems of the flesh have to be changed.
 

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RR has a nice piece on this in the law of moses......"The sockets of brass show us their standing in the flesh: the Setting of the sockets in the earth, their placing among the people to whom the testimony was delivered; the shittim wood of which the pillars were composed, the failing nature in which their service was rendered; their silver mountings, the spiritual garnishings which qualified them for divine employment: the hooks, the pins stuck in the earth, and the cords connecting the pillars with the pins for support—the private and faithful coadjutors who upheld them in their work."