The title tells the story. With brevity and clarity the author explains the importance of the amateur to the professional observer. His list of all the (from arch-to-zoo) gives not only the definition, but what is not known that could be found out by the dedicated layman. Repeated reference to contemporary teenagers, the things that have been accomplished recently (and those rewarded by rious scientific scholarships and study grants) are the living proof of the author's contention that the unknown is knowable. Amateur scientists apply. Especially useful as a fund of suggestions for science projects at the high school level.