Tolstoy's poetry had certain qualities that made it unusual and even unique, one being the "half-spoken" nature of the verse. "It's good for poetry when a thought is only half-fulfilled, so that readers can complete it – each in their own way," he explained in a letter to Sophia Miller in 1854. This view translated into a technique of writing. One of the things Tolstoy was criticized and even jeered for were "bad rhymes" which he used consciously, as part of his "poetic system". "Imperfect rhyming, if kept in bounds of course, can be seen as corresponding to the Venetian school in painting which with little imperfections, or should I say, carelessnesses, could achieve the kind of effects which Raphael wouldn't dream of for all of his precision," Tolstoy wrote in 1859. In fact, Tolstoy, as I. Yampolsky pointed out, was a master of versification. Consciously imposed "careless" rhyming gave his poems an improvisational tone (with "an impression of thoughts being put to paper exactly in the form they were born") but behind it there was hard work and much editing. "Tolstoy's verse is so simple it hardly rises above prose, yet the poetic impression it carries is perfectly full," critic Nikolay Strakhov wrote in 1867. Another unusual feature of Tolstoy's poems was the fact that, while rather salon-like and graceful both in nature and form, they were full of 'simplistic' bits borrowed freely from common talk and traditional Russian folklore. Kept in perfect balance, these tinged his verse with a peculiar, musical quality. More than half of Tolstoy's poems have been put to music by leading Russian composers like Tchaykovsky, Rimsky-Korsakov, Musorgsky, Mily Balakirev, Cesar Cui, Anton Rubinstein, Sergey Rakhmaninov and others. "Tolstoy is the unfathomable well of poems crying for music. For me he is one of the most attractive poets," wrote Tchaykovsky.