Bely’s works tend to focus on the apocalypse, while bridging life and art, because he was a Symbolist (to use the term Bely used for his concern for the ties between man and the transcendent). He also loaded his works with rhythms, alliterations, and neologisms for this reason. Bely defined Symbolism not merely as a literary device, but rather as a “radical epistemological stance” – a new form of cognition. Bely believed that this new cognition, often based in visual perception, would transform mankind (Alexandrov p. 3). To express these beliefs, Bely’s works involved three significant components: the individual, the material world, and the otherworldly realm (Alexandrov p. 4).

Bely, like Kandinsky, used musical terms to identify his works. He wrote four Symphonies, which ere unique fictional prose forms. Their most striking facet was their fragmentariness – the paragraphs included were often linked only metaphorically or by means of leitmotifs. The reader has to work to become involved in deciphering the texts to a much greater extent than was traditional during the era in which they were written.

Thematically, all four works are primarily concerned with symbolic cognition, a dualistic world of matter and spirit, and the apocalypse – whether universal, personal, or both (Alexandrov p. 5).

In Symbolism, which is deeply connected with anthroposophy, in that both involve the same goal – transcending the human reality to achieve a new, deeper spirituality – the Symbolism is both a concern of the work as well as the agent which controls the form and texture of the work (Alexandrov p. 6).

Several of Bely’s works contain strong anthroposophical elements. Kotik Letaev, for example, was written when Bely was completely immersed in anthroposophy. According to Northwestern Press, Kotik Letaev (1922) is

one of the most important works of twentieth-century Russian prose and the great symbolist novel of childhood. It depicts the emergence of consciousness and its development into self-consciousness in a Russian boy growing up among the Moscow intelligentsia in the 1800s.

As compared to Petersburg and The Silver Dove, other works of Bely, Kotik Letaev does not contain the same political, literary, or even plot elements. There is an even greater reliance on musical devices. One of the key images of the book is that of fire, which is repetitively associated with life before birth.
According to Gerald Janecek, who translated the book into English in 1999,

(In Kotik Letaev) the child gradually experiences the three areas of human nature described by Steiner in Theosophy: the body, the soul (ego) and the spirit. Kotik also retraces the historical evolution of the human race (World Soul) as presented in The Occult Mysteries of Antiquity, as well as ascending the stages of Higher Knowledge, and there are indications that he encounters the Guardian of the Threshold. The doctrine of colors also plays a role in the novel. In fact, Kotik Letaev is virtually saturated with anthroposophical imagery and ideas.

Sources:
Gies, Marie L. Rev. of Kotik Letaev, by Andrei Bely, tr. by Gerald Janecek. Slavic and East European Journal, Vol. 16, No. 3 (Autumn 1972), pp. 347-349. April 9, 2008. http://www.jstor.org/stable/305855