Every child has believed something wonderful because a parent said it with a straight face. Mary Carolyn Davies's "Subway Train" is built on exactly that moment. The speaker is a young girl who is certain her father owns a subway train, and who can even tell us how he made it: he took a mole from deep underground, fitted him with iron wheels, and stuck a lightning bug on his head for a headlamp. The poem is a small act of ventriloquism. We hear the child, but we can also hear, just behind her, the father's gentle, inventive teasing.
The central idea is the pleasure of belief, and the way a child's trust turns the ordinary into the marvelous. Notice how the speaker defends her claim. She does not offer evidence about the train; she offers evidence about the teller. Her father wears "a uniform of blue" and "a coat with shiny buttons, / As policemen do," and, most importantly, "he was the one who told me this, / So I know it's true." That last line is the poem's quiet joke and its quiet truth. For a child, authority is not something proved but something loved. Her logic is airtight within her small world: Father said it, therefore it is so.
The imagery is what makes the story irresistible. A subway is a dark, noisy tunnel, and the poem answers that darkness with a creature who already lives in it. The mole is "great big," a phrase with the roundness of a child's vocabulary, and he lives "far underground," so the invention feels natural rather than random. Then come the "iron wheels," giving the soft, burrowing animal a hard, mechanical body, and finally the lightning bug, a living lantern, "to show the way around." Machine and nature are stitched together. The father has explained a loud, mysterious piece of city engineering by turning it into a pet. It is a clever answer to the question every curious child asks, which is how things work, and it lets the child feel that the frightening dark below the street is staffed by friendly animals.
The construction mirrors this simplicity. The first two stanzas are six lines each, and the last is a two-line couplet that works like a punchline. The rhymes in the longer stanzas are plain and satisfying: "blue" with "do" and "true," "ground" with "found" and "around." The speaker's reasoning is carried by her rhymes, so that "do" and "true" snap into place with the same confidence she feels. The meter is bouncy and loosely iambic, closer to a nursery song than to a lecture, and some lines are noticeably shorter than their neighbors ("As policemen do," "So I know it's true"), which makes them sound like afterthoughts a child tacks on for emphasis.
The final couplet deserves a closer look. "My father has told me again and again / That's how he made his subway train." The repetition of "again and again" gives away something the child does not notice. A story told so many times is a family ritual, a bedtime performance, and the father clearly enjoys giving it. The child hears a fact; the reader hears affection. That gap between what the speaker understands and what we understand is the poem's real subtlety. We smile at her innocence, but we are also invited to admire a parent who would rather give his daughter a lightning-bug-lit mole than a dull explanation.
What makes the poem worth reading is how much it does with so little. It is light verse, written in a child's voice, yet it captures a truth about childhood: wonder often comes secondhand, passed down in a trusted voice, and it lasts precisely because it is believed. The poem asks us to remember when a father's word was enough to make the world larger, and a subway a little less strange.