Who says that leaves are green

[dukealien]

Who says that leaves are green
Or sky is blue?
Who says that days are always light
Or night is immanently dark?
 
Who says what anything is really like?

Who says I have to be like you?
Who says you have to be like me?
For your green may be my blue
My light may not be light for you
 
… and my colors change as seasons go.

[Without looking at the other critiques, forgive any repetition]

An interesting Socratic poem, which for that branch of philosophy might arrive at ideal forms (of leaves, colors, etc.).

One thing you might try is replacing the verb to be with more active or diverse (e.g. "Or night lurks, immanently dark?")  This would reduce the didactic nature of the poem, though that is also one of its charms.

The variant interpretations toward the end are also quite nice:  "My light may not be light for you" suggests meanings for "light" beyond the physical--- spiritual, illumination.  And the last line could reference the grue-bleen hypothesis (that something green today might be blue tomorrow - in ideal form, not just the vagaries of the seasons).

One thing (if no one else has mentioned it):  on this board, use of traditional poetic typography (capitalizing the first word of each line regardless of sentence struction)  is frowned upon by some and considered archaic.  I disagree, but do see their point in that line capitalization can create emphasis where it's not intended.  You might consider going to lower case except where capitalization is otherwise required (proper names, first word of a sentence) and see how you like it.

Asks some interesting questions - good effort.