Is this phrase ok?

I started reading an other book where I read, in its Introduction, the phrase written in bold below (I am quoting the full paragraph in which it is mentioned) which I do not understand because it seems to me the meaning is cut somehow. Or maybe I am missing something. Note that when the bold phrase below ends, a totally new paragraph begins:

I have discovered that as we learn to accept change as a fact of life, and accept grief and growth cycles as a definition of the process that makes us "change resilient", creativity increases. Every time we manifest our personality -some aspect of how we think, what we think, who we like, what we do, how we see and solve a problem, how we express our feelings- every single way we, "Insist on ourselves!" as Emerson would say, we paint a picture of the world to see. The stronger and bolder these pictures become mirror our courage to face crisis and overcome them, using life energy in the service of growth.

For me, the phrase would make sense only if we put a comma between become and mirror, where mirror is a verb not a noun. Otherwise, I am not able to understand this. Please clarify me if you know.

P.S. The paragraph I quoted exists in a book called: Taking Advantage of Adversity: How to Move from Crisis to Creativity

The presenting sentence:

• ??The stronger and bolder these pictures become mirror our courage to
      face crises and overcome them, using life energy in the service of growth.

is crammed with distractions that have nothing to do with the verb mirror,
which is at issue. But if we chop down the sentence to the basics it becomes
incomprehensible, i.e. ungrammatical:

• *The stronger and bolder these pictures become mirror our courage.

This is almost certainly a mistake for a sentence with the construction normally called
the X-er, the Y-er, where the Y component has been left out inadvertently:

• The stronger and bolder these pictures become, the more they mirror our courage.

So the answer to the question is that a missing pronoun (they), coreferential with pictures,
is the subject of mirror. But it's put together ungrammatically in the original.

I had noted in a comment that the bolded sentence in the original was "awkwardly worded, if not outright ungrammatical". Here's why:

The stronger and bolder these pictures become mirror our courage to face crisis and overcome them, using life energy in the service of growth.

To wit: what is the subject of the verb 'mirror'?

• 'These pictures'? No, that noun phrase seems to be the subject of 'become'.
• 'The stronger and bolder'? That doesn't seem to be a noun phrase, and even if it is, it's the complement to 'become' and can't stand as a subject of "mirror".

In the comment from @Yosef Baskin above, he makes the admirable suggestion that the sentence would be more clear as follows:

The stronger and bolder these pictures become, the more they mirror our courage to face crisis and overcome them, using life energy in the service of growth.

Which would make 'they' (referring to 'these pictures') the subject of mirror, leaving the sense intact while avoiding the awkward phrasing. One could also write:

As these pictures become stronger and bolder, they mirror our courage to face crisis and overcome them, using life energy in the service of growth.

It seems that somewhere in the writing or editing process, the sentence got a bit too complex and stumbled over itself.

The author is confusing English idiomatic expressions and mistaking number agreement. He probably wants to say:

The strength and courage depicted in these pictures mirrors our courage to face crises and overcome them [in real life], using life energy in the service of growth.

The author is saying, to use an American expression, "fake it 'till you make it." Act like you are strong and courageous, then in real life you'll find yourself actually becoming more strong and courageous.