This thesis aims to deepen our understanding of ‘An Cuilithionn’, which is generally considered to be Sorley MacLean’s most important political poem, by examining the main symbol in the poem, the mountain, in its interaction with the secondary symbols, and also the historical-political figures who figure in the poem. Very little detailed work on ‘An Cuilithionn’ has been carried out, and for this reason this thesis has to establish a sound foundation for research on ‘An Cuilithionn’. A multi-disciplinary approach allows a fuller understanding of the poem to emerge. The specific aim of the thesis is to understand more fully how heart and mind interact in MacLean’s vision of the hero on the mountain. I view ‘An Cuilithionn’ as MacLean’s meditation on human nature and, because this poem was composed at a time when many of the Scottish intelligentsia of which MacLean was part were assessing their own views on action and pacifism, I also postulate that in ‘An Cuilithionn’ MacLean contemplates the nature of his own identity in that light. The argument of the thesis is based on the premise that in ‘An Cuilithionn’ politics significantly contribute to how MacLean views heroism and his identity is defined by how he perceives figures of history such as Lenin, Dimitrov and James Connolly. I use the psychological approaches of both Julia Kristeva and C.G. Jung as well as the literary theory of Northrop Frye to gain a broader perspective on the topic. In Chapter 1 MacLean’s literary influences as well as the contemporary literary and political climate of Scotland in general are examined. In Chapter 2 and 3 I define the theoretical framework of my inter-disciplinary approach to the subject. In Chapter 4 I speculate whether the main symbols in the poem, the mountain and morass, originate from MacLean’s own personal view of the universe and in Chapter 5 I examine the secondary symbols, the seamonster and stallion, which reflect the personal and political themes in the poem. The dynamic, which I propose is present in the symbols that I have already looked at in the previous chapters, is further considered in Chapter 6 in relation to MacLean’s ideal of the self-sacrificed hero using, in particular, James Frazer’s meta-narrative of the dying and reviving god and Northrop Frye’s literary myth of death and rebirth. In Chapter 7 I connect the theme of self-sacrifice in ‘An Cuilithionn’ to MacLean’s use of Hugh MacDiarmid’s poem, ‘If there are bounds to any man’, which he incorporated into Part V of ‘An Cuilithionn’, and I show that MacLean’s socialist ideals are inextricably linked to his belief in the eternal striving of the hero, which leads him towards a fuller understanding of the course of mankind as a whole. This thesis raises the question of how MacLean views the individual and the collective as well as the personal and the political. It also explores MacLean’s responses to his major influences such as Communism and religion and examines how he deals with these in both an intellectual and emotional way.