'The arrow speeding'

I recently came across this poem, of two short and simple stanzas, in R.S. Thomas's Mass for Hard Times:

Target

I look up at the sky at night
and see the archer, Sagittarius,
with his bow drawn, and realise
man is the arrow speeding,

not as some think infinitely
on, but because space is curved,
backwards towards the bowman's heart
to deal him his unstanched wound.

I wonder if, when he wrote it, Thomas was remembering his use of the same image of the returning, self-wounding arrow in his moving earlier poem Sorry, addressed to his forgiven parents:

Dear parents,
I forgive you my life,
Begotten in a drab town,
The intention was good;
Passing the street now,
I see still the remains of sunlight.

It was not the bone buckled;
You gave me enough food
To renew myself.
It was the mind's weight
Kept me bent, as I grew tall.

It was not your fault.
What should have gone on,
Arrow aimed from a tried bow
At a tried target, has turned back,
Wounding itself
With questions you had not asked.