Final answer:
The poem is classified as a sonnet despite deviating from traditional form, as it maintains the basic structure of fourteen lines and a volta. Poets like Millay experiment with the sonnet form to bring a fresh perspective to their work.
Step-by-step explanation:
The poem is classified as a sonnet because it maintains the basic structure of a sonnet, which is fourteen lines and contains a volta or turn in thought. However, it deviates from the traditional form by reinventing the structure, such as using different rhyme schemes or meter, or even completely disregarding them. This allows poets like Millay to experiment with the sonnet form and bring a fresh perspective to their work.