"Thinking is not entertainment but an obligation!"
Boris and Arkady Strugatsky
"Arkady Natanovich Strugatsky and Boris Natanovich Strugatsky are probably the most famous Russian SF authors. They became the spiritual leaders of Russian science fiction literature in the 60-s, and to this day, their influence remains immense.
Entire generations were brought up on their books, and the authors managed to impress their ideas and principles on millions and millions of people. The number of their fans in Russia is really impossible to count, and even abroad, their works have found way to the hearts of the readers. The key to their success is, in their own words, that they write "about adventures of the spirit, and not about adventures of the body.
Any Strugatskys' work is very different from an ordinary SF book in that it is not 'pure science fiction.' Strugatskys always write about people and their problems, and not about spaceships, technology or other things that the ordinary SF literature is full of. There are so many layers of ideas and thoughts in their works that you have to read them several times if you want to really grasp all that authors packed in. Their books stir up the desire to understand other people."
Source: Russian Science Fiction and Fantasy
Boris and Arkady Strugatsky - Wikipedia