Task: Question Answering
Input (English): Passage: Tchaikovsky struggled with sonata form. Its principle of organic growth through the interplay of musical themes was alien to Russian practice. The traditional argument that Tchaikovsky seemed unable to develop themes in this manner fails to consider this point; it also discounts the possibility that Tchaikovsky might have intended the development passages in his large-scale works to act as "enforced hiatuses" to build tension, rather than grow organically as smoothly progressive musical arguments.According to Brown and musicologists Hans Keller and Daniel Zhitomirsky, Tchaikovsky found his solution to large-scale structure while composing the Fourth Symphony. He essentially sidestepped thematic interaction and kept sonata form only as an "outline," as Zhitomirsky phrases it. Within this outline, the focus centered on periodic alternation and juxtaposition. Tchaikovsky placed blocks of dissimilar tonal and thematic material alongside one another, with what Keller calls "new and violent contrasts" between musical themes, keys, and harmonies. This process, according to Brown and Keller, builds momentum and adds intense drama. While the result, Warrack charges, is still "an ingenious episodic treatment of two tunes rather than a symphonic development of them" in the Germanic sense, Brown counters that it took the listener of the period "through a succession of often highly charged sections which added up to a radically new kind of symphonic experience" (italics Brown), one that functioned not on the basis of summation, as Austro-German symphonies did, but on one of accumulation.Partly due to the melodic and structural intricacies involved in this accumulation and partly due to the composer's nature, Tchaikovsky's music became intensely expressive. This intensity was entirely new to Russian music and prompted some Russians to place Tchaikovsky's name alongside that of Dostoyevsky. German musicologist Hermann Kretzschmar credits Tchaikovsky in his later symphonies with offering "full images of life, developed freely, sometimes even dramatically, around psychological contrasts ... This music has the mark of the truly lived and felt experience". Botstein, in elaborating on this comment, suggests that listening to Tchaikovsky's music "became a psychological mirror connected to everyday experience, one that reflected on the dynamic nature of the listener’s own emotional self". This active engagement with the music "opened for the listener a vista of emotional and psychological tension and an extremity of feeling that possessed relevance because it seemed reminiscent of one’s own 'truly lived and felt experience' or one’s search for intensity in a deeply personal sense". 
Question: What is the last name of the person that wrote that listening to the music of the man who struggled with sonata form "...reflected on the dynamic nature of the listener’s own emotional self"?
Output (English): Botstein.