Explain the quote, "Only the deaf appreciate hearing,only the blind realize the manifold blessing that lie in sight."

The quote reflects the basic idea that there are
attributes and qualities that all learners have. At the same time, the quote reminds all
of us of the qualities that are so easily taken for granted, yet appreciated by those
who are impacted by their absence.  For example, someone who is hearing impaired, or
"deaf," will value the ability to hear because it is something they lack.  The person
who possesses this sense might not appreciate it as such because they are more likely to
take it for granted.  The same applies to those who are vision impaired, or "blind." 
They would appreciate sight, whereas someone who has it might not appreciate it as
much.  In the end, the quote compels all of us to appreciate what it is we have.  Too
often, individuals lament what they lack and what they don't have.  The quote might be
suggesting that to be thankful for what basic elements are present will allow
individuals to lead a more purposeful life, one with meaning, compassion, and
understanding.  In this light, the quote both makes a point about those who face
significant physical challenges in their lives and those who do not.  Helen Keller
becomes the epitome of those individuals who are able to embrace what they have,
allowing life to become a more purposeful existence and not being defined by any
physical condition.