The theme of the poem on a profound level is loss of control (a train you can't get off) and on a shallower level - pregnancy. The woman in the poem likens herself to a metaphor for something else - she has lost control of her body and her future so she is seeing this (at this moment) in a negative pessimistic light. This is highly relevant when we consider her mental health issues.She sees herself as secondary in importance now to the child, the future and probably the father (the poet whom she is supposed to 'made' famous - given birth to in another sense - Ted Hughes the famous English Nature poet.) If it is true that Hughes contributed to her suicide by his womanizing and leaving her all alone trapped in a freezing cottage on the moors, then we could certainly see the poem as a complaint - as a part of that feeling of injustice. However, mental health issues are very complex and it may have been more than an untrained husband could deal with. She later killed herself after separating from Hughes. Plath is now a major study subject in feminist writing and certainly those issues of identity,role and independence come out in her poetry and in this poem.
Here's the poem:
I'm a riddle in nine syllables,
An elephant, a ponderous house,
A melon strolling on two tendrils.
O red fruit, ivory, fine timbers!
This loaf's big with its yeasty rising.
Money's new-minted in this fat purse.
I'm a means, a stage, a cow in calf.
I've eaten a bag of green apples,
Boarded the train there's no getting off.
THEME: The expecting mother feels like a means to an end; she has become a devalued host. She's suffering from a kind of pre-partum depression. She describes herself in bloated imagery compared to the more valuable baby inside her. She is an elephant that hunters might want to kill for its tusks (the baby). She is the purse that one might want to steal for the money. She is the ponderous house one might want to raze for its fine timber.
FORM: It's a 9 by 9 poem: 9 syllable; 9 lines. 9 for the 9 months of pregnancy, of course. It's titled "Metaphors" because she's bombarding her reader with them. The poem has two sets of metaphors. Each "mother" metaphor matches up with a "baby" one.
(MOTHER) vs. (BABY)
- Riddle vs. nine syllables
- Elephant vs. ivory
- House vs. fine timber
- Melon vs. red fruit
- Loaf vs. yeast
- Fat purse vs. money
- Means/stage vs. (implied)--"end"
- Cow vs. calf
- Bag vs. green apple(s)
- Train vs. (implied)--"passenger"
TONE: The poem is a sort of complaint, not aimed at the baby, of course. It's aimed at others who see through her, those who are interested in her baby and her pregnancy more than her. You know the people who ask the same old questions: "When are you due?" "Are you hoping for a boy or a girl?" Maybe it's a complaint toward motherhood. Maybe toward her mother or the mothering types. Maybe toward her body. It can be read playfully (as resignation), and it can be read darkly (as anxiety). Regardless, she's going to have the baby (i.e., she's "boarded the train; there's not getting off").