This study examines how Seamus Heaney modulates tones and operates mood in his poetry, focusing on a few works dealing with his childhood and memories in Death of a Naturalist. In some of his earlier works, he described how a growing young man had undergone unpleasant transformation. The speaker pretends to assume an objective attitude toward what really happens in daily lives. He seems to keep his composure and speaks in a calm tone. However, his underlying tone also shows his pity on things. Consequently, his tones show the situation ironically, which produces the mood of pathos effectively. Besides tones, unique structure, sounds, and even sentences create irony and contribute to his pathetic mood in subtle ways. This is the way he manages his personal remembrance and Irish matters. The way of handling personal experiences and issues ironically confirms his modern technique. Another goal of this study is to know what features Heaney`s pathetic mood and how it will develop. In his later works, Heaney thinks highly of maternal tolerance and some critics find so-called "female principles" in them. His pathos in earlier works functions as a prop in the development of his later works respecting feminine sensibility. The strength of this feminine quality is that it can sympathizingly embrace all troubles of life. His pathos contributes to his attitude to connect sympathetic sensibility with positive values of life in his later works.