I say her phrases to myself/ in my head
Duffy writes in the first person and the reader is immediately drawn into her personal thoughts and feelings. She links herself with her mother in a sentence that mixes "her phrases" with "myself" and "my head"."Her" is possessive suggesting the words belong to her mother but the fact they are in “my head” clearly shows a deep and personal bond.
under the shallows of my breath
Duffy is saying the words quietly to herself. Shallow breathing suggests anxiety - she is nervous on this journey. Perhaps she is repeating her mother’s words to comfort herself.
The word "shallows" has connotations of water and perhaps recalls the sound waves themselves merging with the poet's own breathing. This implies that her mother's sayings are integral to her very existence.
They become "restful shapes moving," which suggests the daughter is soothed by them. This links the words with the journey.
The line relates to the journey taking place, as scenes and landscapes that are still or resting seem to move when viewed from a train. "restful" and "moving" is a contradiction which perhaps links to the fact that on a train you seem to be still while the rest of the world races past you.
Although it is Duffy who is on a journey, this seems like a moment of stillness and reflection while it is the world that changes around her.
"Moving" can also be seen in another sense, suggesting the poet’s feelings - the phrases and journey are emotionally moving.
The day and ever. The day and ever.
Just as Duffy has linked her mother’s words with what she sees through the window, now she uses a repeating phrase to suggest the sound of the train. The repetition mimics the rhythm of the travelling train. It also suggests the poet repeating the words to herself, calming herself.
Italics stress the importance of the phrase and show that this is a direct quotation - one of the mother’s phrases.
The use of "ever" at the end of phrase refers to eternity, as if this journey will last her whole life and this connection with her mother will always be there.