A. Moore reviews "African Writing Today," an anthology edited by Ezekiel Mphahlele. Excerpt: "In a field where the number of anthologies threatens to outstrip the output of original work, where the same stories and poems tend to crop up again and again, and where collection of texts is too often offered as a substitute for critical evaluation, the appearance of a new anthology seems to present a suitable occasion for demanding the purpose of it all... At the other end of Africa, Ama Ata Aidoo of Ghana discovers her [compassion] by feeling for the thread of their speech as it strives to catch hold of meaning in a dark stream of events..."