In order to tackle this question and try to avoid repeating what other educators have said, I'm going to move through the point to pull out specific points where Sor Juana mentions expectations that men have on women, and why this is a problem. The poem is a sharp critique of the injustices that she's experienced first hand as a woman, and it's a powerful calling out of the men who hold women to these impossible standards.
She says that men are urging perfection while making it harder and harder to reach that unrealistic ideal. She complains that men contradict themselves by requesting women to stand up for themselves but also be calm and gentle.
As was previously mentioned, she also accuses men of demanding that women be virgins, while they themselves celebrate having sex.
She says men complain if a woman does something wrong, but mock her if she does everything correctly. In the same way, if a woman rejects a man she is cruel, but if a woman accepts him she is easy and promiscuous.
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