The speaker is addressing a baby, and the poem follows the early milestones of the child's life. First comes rolling over, which happens once and then keeps happening until the baby tumbles and cries. The speaker cries too, afraid something terrible has happened. But the falls repeat, and slowly both of them get used to it. Then comes the next step: the child stands up, and the speaker is startled, while the baby seems calm, almost as though standing were something they had always known how to do.
The mood is tender, a mix of worry, surprise and quiet wonder. The trailing dots slow the lines down and suggest repeated attempts and a sense of time passing. The final line is the heart of it. Watching the child's confidence, the speaker seems to see parents differently, as strange and remarkable "creatures" who live through all this fear and amazement. The poem suggests that becoming a parent is a matter of learning alongside your child.