Oblong 16mo. 89pp. Presumed first edition. Illustrated throughout with text figures by Hebe Gomes. According to the author's Preface to instructors, the content of this volume - the third and final in a series - is aimed toward educating secondary and technical school students. Cabral lays out the structure of the work on page 16 - presenting ten sections that contain four or five subjects that treat aspects of art and technology through poetry, musical arrangements by Estefânia Cabreira, and the very striking illustrations. Among the subjects receiving this treatment are the printing press, the steam engine, hydraulic turbines, the grain harvester, the sewing machine, which is then balanced against various fine arts, such as painting, sculpture, poetry and music. It is therefore more a philosophical view of human progress than a traditional school textbook, per se, its appearance made even more curious by the fact that it was published during the early years of the Salazar dictatorship. Unlike children's books from other authoritarian regimes during this time, Cabral's work lacks any overt attempts at indoctrination. Unrecorded in any institutional holdings. Slight toning and edgewear; very good overall in original cloth-backed color printed boards.