The ark of consequence 

The classic rainbow shows as an arc, a bridge strung 
in thinning clouds, but I have seen it flash a perfect circle,
 rising and falling and rising again 
through the octave of colors, 
a sun shape rolling like a wheel of light. 

Commonly it is a fraction of a circle, a promise only partial, 
not a banal sign of safety like a smile pin, that rainbow 
cartoon affixed to vans and baby carriages. 
No, it promises only, this world will not self-destruct. 

Account the rainbow a boomerang of liquid light, foretelling rather 
that what we toss out returns in the water table; flows from the faucet 
into our bones; what we shoot up into orbit falls 
to earth through the roof one night. 

Think of it as a promise that what we do continues in an arc 
of consequence, flickers in our children’s genes, 
collects in each spine and liver, gleams 
in the apple, coats the down of the drowning auk. 

When you see the rainbow iridescence shiver in the oil slick, 
smeared on the waves of the poisoned river, shudder 
for the covenant broken, for we are given only this floating round ark 
with the dead moon for company and warning.

§ Marge Piercy

In The hunger moon : new and selected poems, 1980–2010 / by.—1st ed.