NONFICTION : COLLECTING SOULS, GATHERING DUST by <i> Gerald Belcher and Margaret Belcher (Paragon House: $22.95; 320 pp.)</i> .

This is one of those books that makes you sigh for what might have been. Alice Neel and Rhoda Medary, painters who met at art school in the 1920s, are a fascinating pair--the former the first woman to have a solo show at the Whitney Museum, the latter a talented woman who chose family over career. Neel lived a life of public satisfaction and private disarray, while Medary stockpiled her artistic efforts in a basement; the two were reunited 53 years after their first meeting when Medary attended the Whitney show. The authors provide glimpses of their intriguing lives, but they falter, fatally, by imposing an agenda on their material. The purpose of this book is to examine “the problems faced by women in this century who wanted to be serious artists.” An honorable undertaking, surely--but lives cannot be forced into rigid molds without losing the spontaneity that made them interesting in the first place.