I too beneath your moon, almighty Sex,
Go forth at nightfall crying like a cat,
Leaving the lofty tower I laboured at
For birds to foul and boys and girls to vex
With tittering chalk; and you, and the long necks
Of neighbours sitting where their mothers sat
Are well aware of shadowy this and that
In me, that's neither noble nor complex.
Such as I am, however, I have brought
To what it is, this tower; it is my own;
Though it was reared To Beauty, it was wrought
There’s a prominent trend in Western thought (quoting  Tocqueville  but it’s much older, to Aristotle, etc.) that human beings have “noble passions” and “base passions”, and that we should cultivate the former and suppress the latter. 
 
 “Noble” or complex passions, are things like appreciation for poetry, fine wines, classical music, making peace and polite conversation with one’s fellow gentlemen and ladies. 
 Lust, the desire for sex, desire for food, reality television, lubed condoms, etc. are strictly “base” and not to be encouraged. But Millay defiantly admits here that she is at bottom NOT noble, NOT complex, and in the next line, she justifies why that’s okay.
I Too Beneath Your Moon Almighty Sex