
Originally Posted by
emka
Not a teacher
I don’t think it is either.
To me “Life has its roses and thorns” looks like a metaphorical extension.
And I don’t think it’s even a very good one, at least not for the purpose of grammar explanation, because the two things it compares are not on the same conceptual level.
Good and bad > roses and thorns. I admit it sounds poetic. But being parts of the plant (like petals, stem, leaves) “thorns” are a sub-category of “rose” while “bad” is not a subcategory of “good” but the opposite. A formally balanced, same-level metaphorical extension would have been “Life has its roses and thistles”, for example.