The poem speaks of a "holy tree", growing within the reader's heart, glorious and strong-rooted - full of life. It also speaks of a tree that is viewed "in the bitter glass" - which more or less would be the opposite of "rose tinted glasses" (crap-tinted glasses?). The reader is presented with the choice of where to spend their focus.
This became somehow entwined, this morning, with the Robert Frost lines-
Two roads diverged in a wood, and I--
I took the one less traveled by,
And that has made all the difference.
It's absolutely true. Although one should aim to focus on the present moment, not defining one's self in terms of "my story so far", it still strikes me that the lesson I learned back then, which has resulted in my (more often than not, anyhow) choosing to walk the brighter road... has made all the difference.
Beloved, gaze in thine own heart.