Voces Intimae is unquestionably a work of central importance in Sibelius's output. Like the last tone poem Tapiola it relies to an extraordinary extent on the minor keys: from the contemplative opening to the fanatically intense closing bars the mood is predominantly solemn. What makes the quartet different from Sibelius's other "introspective" works is that it expresses human suffering rather than the power, brutality and craggy beauty of nature. The composer's own words, "Voces Intimae", reinforce this concern for individual humanity.