This is not an easy poem to explicate. I won't list all of the poetic devices Jonson uses, but here are a few examples to get you started.
allusion: there are several references to characters from Greek mythology, such as dryads, Bacchus, Pan, the Muses, satyrs, fauns, etc.
alliteration: in lines 12 and 13 there are the "broad breech" and "taller tree"; in lines 28 and 29 we find "purpled pheasant" and "painted partridge"
rhyme: the poem is a series of couplets that rhyme AABBCCDD etc.
imagery: food, plants and animals
personification: in line 21, the house is spoken of as a host who feasts or exercises friends; in lines 32 and 33 the ponds pay a tribute (like a tax) to the house
You might say that the entire poem is a metaphor for England: just as Penshurst is the ideal, flourishing house, so also England is the ideal, flourishing nation.
I hope this helps you. As I said before, this is not an easy poem!
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