"Practical Aesthetics" by G. Semper was devoted to the analysis of the essence of subject art forms - in contrast to fine art forms; the relationship between form and ornament; the problem of the emergence of increasingly complex, symbolic ornamental forms, which are able to exist independently, outside the environment within which they arose. It was supposed to end with a teaching about style in architecture. Based on this teaching, G. Semper dreamed of further comparing "technical" and "tectonic" types of art with other works of art, "high" types of art. But this section remained undeveloped. The works of G. Semper are published in Russian for the first time.