* "If you be a poet, write a poem": This emphasizes the action of writing as the defining characteristic of a poet. It suggests that if you want to be considered a poet, you need to produce poetry.
* "If you be a poet, your poem": This implies that a poem is a reflection of the poet themselves. The poem embodies their thoughts, feelings, and experiences.
It's important to note that the original meaning, if any, is unclear without context. It could also be a creative play on words with no specific meaning intended.
If you encountered this phrase in a particular context, please provide more information so I can help you understand its intended meaning.