African-American poet Langston Hughes in his poem below urges Americans to celeb

African-American poet Langston Hughes in his poem below urges Americans to celebrate the freedom they enjoy and remember that freedom has always been incomplete. Discuss two examples that best illustrate his point from the cannons of history:
There are words like Freedom
Sweet and wonderful to say.
On my heartstrings freedom sings
All day everyday.
There are words like Liberty
That almost make me cry.
If you had known what I know
You would know why.