Caught Writing "Blackberry Eating"

A great poem, a great play on words all through. Galway Kinnell creates a very clever metaphoric connection between actually eating blackberries and writing poetry. He manages this with such lines as "the ripest berries fall almost unbidden to my tongue, as words sometimes do". In fact, only the first few entry lines describe the setting and sense of emotions/feelings when eating blackberries, or picking blackberries. After that one line, Kinnel's metaphors slowly unravel themselves. Unbidden berries fall on his tongue, as does that great eureka moment. 

Speaking of unbidden events, as i read through this a couple more times for this post, i noticed its repetitive use of certain letters. At the beginning Kinnel throws a barrage of B's and the word black, "icy, black blackberries to eat blackberries for breakfast... the black art of blackberry-making". Then near the end, he does so again, this time with S, "one-syllabled lumps, which i squeeze, squinch open, and splurge well in the silent, startled, icy, black language". And the use of the word "icy" is very interesting, not quite sure why...