need help translating a phrase

[yellowjello]

I encountered this while reading a manga. I included the kanji for the words I am not sure about. Even after looking them up on denshi jisho, i'm not sure how they fit in with the meaning of the sentence as a whole.
ayamachi wa hito no ayumi wo tomeru kase ni arazu. kokoro wo sodateru (育てる) kate(糧) de aru.
I know what the individual words mean, but I am having trouble piecing them together. what i have for a very rough translation so far is:
The mistake isn't the shackles that hold people back. It's the (provisions?) of the maturing heart.

Can someone help me fix my translation?
Thanks in advance.

 

[Toritoribe]

心を育てる糧である。
It's nourishment to mature one's heart.

As you might notice, kase and kate rhyme.

 

[yellowjello]

that makes a lot more sense now. i couldn't think of the right word to translate it with. thanks!