Not less because in purple I descended
The western day through what you called the loneliest air,
Not less was I myself.
What was the ointment sprinkled in my beard?
What were the hymns that buzzed around my ears?
What was the sea whose tide flowed through me there?
From my own mind that golden ointment rained
And my ears made the blowing hymns they heard
I was myself the compass of that sea.
I was the world in which I walked, and what I saw
Or heard or felt came not but from myself.
And there I found myself more truly and more strange.
Through this experience, it conveys a sort of ostracism to the speaker—it makes him feel alienated from this  elite environment. 
 
 The speaker is satisfied with his world, but these external stimuli caused grief with his formerly held disposition. Such events made the speaker reconsider his perception in general. This/these experience(s)  grounded  him, from which he found himself “more truly and more strange,” perhaps from the shock which his perceptions sustained, with this  elite environment. 
 The interplay of the “true” and the “strange” is of the essence of poetry. Take Isabella from the last scene of  Measure for Measure , 5.1.: 
 
 ISABELLA Most strange, but yet most truly, will I speak: That Angelo’s forsworn; is it not strange? That Angelo’s a murderer; is ’t not strange? That Angelo is an adulterous thief, An hypocrite, a virgin-violator; Is it not strange and strange? 
 DUKE Nay, it is ten times strange. 
 ISABELLA It is not truer he is Angelo Than this is all as true as it is strange: Nay, it is ten times true; for truth is truth To the end of reckoning. 
 
 or again, pieces of Stevens' own “The Man With the Blue Guitar” 

Tea at the Palaz of Hoon