Certainly Miss Sarton's expository poetry with its rhyming words that clank like coupling railroad cars is for a quite undemanding audience. ""Now we have silenced the voice we never heard/ Break open, heart and listen to his word."" Occasionally, however, she releases rhetorical postures into true feeling: ""Sweet night nursing a neighbor -- / The old lady lifts her hands/ and writes a message on the air -- /"" This direct engagement, unfortunately, is a sometime thing, even in the poems about animals, her special province. In ""Bears and Waterfalls"" the charmingly sportive "". . . great brown queen/ Sleeked down in her rough silk/ Flirting with her huge lord/ Breast-high in her tureen --"" reduces to ""And childhood's rug come true."" Most of these poems deal with Miss Sarton's distress at the ugly passions let loose upon the world. For the following -- a few songs at twilight.