Stele 666
Liber 25 The Star Ruby
FLEGEI GAR PERI MOU O ASTHR TON PENTE,
KAI EN THI STHLHI O ASTHR TON HEX ESTHKE.
Here's a few thoughts to start the ball rolling.
In the previous verse the symbolism of the Hexagram appeared. I think this verse completes what the other one started. (9+10=19. Atu XIX The Sun). In verse 9 RHK says, "thus shall my worship be about my secret house". This suggests a circle to me. In this present verse the focus seems to shift to the point at the centre of the circle, making the glyph of Sun. For this reason I think the attribution of Atu IX The Hermit - Yod fits quite well.
On the surface this verse appears to be telling us to get the actual funerary stele of Ankh-af-na-Khonsu. But as far as I know it's still in an Egyptian museum. So what is this? A Thelemic version of the movie, Highlander. "There can only be one!"
But I don't think that is what is being said here. Note that it says to get the stele itself. The stele is a symbol of something else, and it is this reality behind the symbol that is to be set inside the "secret temple". I think two of the most basic summaries of the imagery on the stele are the glyph of the Sun and the hexagram. (Hermit's lamp. Locked glass.

) Two opposite principles coming together to make a third. Nuit + Hadit = RHK.
Glory to thee, eternal Sun
Thou One in Three, Thou Three in One!
It is this internal Sun, LVX, HGA etc., that is the Kiblah to which we turn to pray and worship. Any physical stele/sun that we might turn to in worship is an exterior symbol for this inner way.
The word stele also makes me think of the column in the pentagram rituals. See above for the Star Ruby version.
For about me flames the Pentagram,
And in the Column stands the six-rayed Star.
The circle of pentagrams is symbolic of Nuit. While the column in the centre is Hadit. Essentially it is a symbol of the Phallus joined with the Yoni. This brings to mind a couple of verses from Liber LXV.
Liber LXV 5:5-6
Now is the Pillar established in the Void; now is Asi fulfilled of Asar; now is Hoor let down into the Animal Soul of Things like a fiery star that falleth upon the darkness of the earth.
Through the midnight thou art dropt, O my child, my conqueror, my sword-girt captain, O Hoor! and they shall find thee as a black gnarl’d glittering stone, and they shall worship thee.
The phrase "locked glass" seems problematic at first. It appears to run counter to any inner symbolic interpretation. Locked suggests something that is fixed in place, while glass is a transparent material that lets light shine through it.
The Intelligence of Beth/Mercury (Ruler of Virgo/Hermit) is the Intelligence of Transparency.
Intelligence of Transparency is the mode of consciousness. "Transparency" means "letting light shine through." Here we have the same idea of transmission that is suggested by Hermes as the transmitter of the messages of the higher divinity. Clearly the mode of consciousness called transparent must be one which affords a free channel of communication, which permits the free passage downward and outward of the superconscious Light which is above and within.
P. F. Case - The Tarot (p.40)
This suggests to me an internal mental (Mercury) image of the Stele or an equivalent, fixed through daily practice. Through this daily Fixing of Mercury the Light(LVX) can shine through it and "miraculous colour shall come back to it day after day."
A proof to the world? Apart from evidence it makes me think both something that strengthens and tests.
This verse is 155 in the book as a whole. 777 gives:
155 - ADNI MLK, Adonai the King
155 - QNH, a seed.
The previous verse was XI Lust. This verse is IX The Hermit.
XI + IX = XX The Aeon.
Chp.III, verse 10 - 310. 777 gives 310 - DVSh. To trample on, conquer.