The world imagined is the ultimate good.
This is, therefore, the intensest rendezvous.
It is in that thought that we collect ourselves,
Out of all the indifferences, into one thing:
Within a single thing, a single shawl
Wrapped tightly round us, since we are poor, a warmth,
A light, a power, the miraculous influence.
Here, now, we forget each other and ourselves.
We feel the obscurity of an order, a whole,
A knowledge, that which arranged the rendezvous,
Within its vital boundary, in the mind.
We say God and the imagination are one…
How high that highest candle lights the dark.
Out of this same light, out of the central mind,
We make a dwelling in the evening air,
In which being there together is enough.
Even if “God and the imagination are one"—if God is imagined, or simply the equivalent of the human imagination—the concept and belief still consoles, still "lights the dark.” 
 Regardless of the existence or nonexistence of any God, the notion comforts. Stevens borrows from biblical imagery to make his point. (Here are  100 verses  about God providing light to the world of darkness.) He also paraphrases Portia in Shakespeare’s  The Merchant of Venice  (V.i):  “How far that little candle throws his beams!” 
 If it is the “imagination” considered as “that highest candle”, the speaker appears to find great comfort from imagination. Imagination here likely includes the full extent of thought, as a “vital boundary” and “rendezvous” is considered, and for the latter of which we “collect ourselves… / …into one thing.” This “rendezvous” is based upon ideas form the first stanza, “the world imagined”. 

Final Soliloquy of the Interior Paramour