I sense that there is a theme of transcendence in Plath's poem. One of the unique features of this poem is that it identifies what Plath thinks of in terms of envisioning a world outside of patriarchal control. In poems like "Lady Lazarus" or "Daddy," there is a strict condemnation for what the Status Quo is. In "Ariel," we see something a bit different offered, a vision of what can be or a transcendence. Plath, herself, articulated this in her journal:
[I]t is suddenly either all or nothing; either you break the surface shell into the whistling void or you don’t.The horror is the sudden folding up and away of the phenomenal world, leaving nothing. Just rags. Human rooks which say: Fraud.
"Ariel" might just represent this idea of "breaking the surface shell." There is a theme of rebirth that is a part of the poem. The taking of the Ariel idea in sacrificing herself in the water, from which the sea- foam emerges is evident in the line, "And now I/Foam to wheat, a glitter of seas." The "cauldron of morning" that ends the poem can be a notion of rebirth, as well. In this, Plath might be suggesting that a transformation of what is into what can be is a part of what it means to be a woman, or even part of the modern condition. There is a shedding of "Dead hands, dead stringencies" in this process, one in which there is a new conception of liberation out of what is. This theme of transformation and rebirth is a major element of the poem.