In Stockman's book, he mentions Bono songwriting when he writes, "When it comes to songwriting, Bono would admit that he didn't discover the art until the group's 1987 release, The Joshua Tree.
I would almost beg to differ, though if Bono said it, then one has to believe that for him, that was his reality. However, I look at U2's 1984 release, The Unforgettable Fire as just as pivotal a release in Bono discovering not only the art, but the gift in his songwriting.
Such lyrics, as "The wind will crack in winter time
This bomb-blast lightning waltz
No spoken words, just a scream..." and
"If you should ask then maybe they'd
Tell you what I would say
True colors fly in blue and black
Bruised silken sky and burning flag
Colors crash, collide in blood shot eyes" begin for Bono a poetic ambiguity to his lyrics that ring with so much passion, that one couldn't help but realize that a deep human emotion was attached to these lyrics.
I truly believe that we have no Joshua Tree without Bono discovery of his true gift and songwriting ability that we find on The Unforgettable Fire, and possibly, not so much Lanois, but Eno who pushes Bono to look deeper inside himself than he ever had before to find this gift, even if it wasn't painted on the canvas in clear, distinct colors.