The world of a child as a topic gave birth to a number of Mussorgsky's decisions concerning figurative modes, music style systems, principles of composition and music poetics. The master captured the microcosm of passions, that originally inhabit the soul of a child, and his works presented an embodiment of the deep, ontological nature of any human personality with its typical mixture of good and evil. In his musical works about children the composer also showed us some fundamental laws of psychology: some child entertainments, that are not quite harmless, conceal future repulsive character traits of an adult; and evident aggressiveness of a person is often a result of a former child having been unjustly insulted. All this makes it possible for us to speak of Mussorgsky as a composer and a child psychologist. [Note: The citation provided on this PDF (volume 10, number 4) is incorrect. The correct citation is volume 11, number 10.]