[No] poet more than Sylvia Plath keeps reminding us of the terms and the ground of her writing. To say that she writes in extremis is not only an accurate statement of fact but a suggestion that more than aesthetic matters may be involved. (p. 127)

Ariel, Sylvia Plath's major posthumously published book of poems, begins and ends in extremis. "Morning Song," the opening poem, begins with the word "love." "Words," the concluding poem, ends on the word "life." The title of the last poem "Words," and the pun in the title of the opening poem "Morning Song" suggest the two other prominent centers here, art and death. Love and death, life and art—these are the extremities out of which the Ariel poems proceed. And Plath insisted upon them and returned to them for alignments of the most dangerous kind.

The Ariel poems reveal and often pursue a...