The saving grace of "music for children,” I find, is that it is never really composed for children, but about them — or more usually about the part of us which traffics in irony, yet yearns to remain simple and pure. There are few lullabies effective for sleep which would long engage an adult mind, so I know Sasha Cooke will forgive me for saying that her stunningly effective rendition of Britten's Charm of Lullabies last Tuesday at Music at Menlo, outwitted Morpheus.