Sor Juana Ines de la Cruz was a writer, poet, composer, philosopher, and nun. She was born in Mexico in 1651 and was among the first great Mexican writers.
During the time of Sor Juana's prominence, women were discouraged from pursuing an education and speaking up for themselves. Sor Juana was not willing to conform, instead pointing out the double-standards and impossible social norms women were expected to follow. Here's a great quote from her poem "You Foolish Men":
No woman wins esteem of you:
the most modest is ungrateful
if she refuses to admit you;
yet if she does, she's loose.
In the same poem she writes:
your censure is unfair;
as she had to constantly fight to make her voice heard. She also demonstrates her power in the poem "Since I'm Condemned":
But as I die without resisting
my unhappy lot, my only wish
is you allow me choose the death I like.
Let my death be of my choice,
for your mere choice
continues me in life.
This stanza demonstrates her character well. She sees the injustice in the situation and determines that she will not protest, but she will maintain a sense of independence even to death. If she must be punished, she'll be punished on her terms.
Another place to find examples of Sor Juana's power and her place in the culture of the time is her "Reply to Sor Filotea."
In this essay, she defends a letter in which she had criticized a sermon and received much criticism for her words. She establishes ethos by first explaining her academic background, writing:
...when I was six or seven years old, and already knowing how to read and write along with all the other skills that women learn such as embroidery and sewing...
She then explains why she decided to become a nun and why she should be allowed to express her opinions despite being a woman. She explains her love for learning and shows that she is learned and just as intelligent as any man. She lists the names of many Biblical women who were allowed to teach and learn.
In short, there are many examples from Sor Juana's writings that show her independence, determination, and bravery. She wanted to be heard, and she wanted to open the way for other women to be able to learn and teach as well.