In connection with the world beyond globalization, new theories such as Samuel Huntington's 'The Clash of Civilization', Gilbert Achcar's 'New World Disorder' and 'The Third World War' are emerging. This paper was motivated by the personal thinking that the Republic of Ireland as Celtic Tiger goes beyond globalization toward 'uisneach', as the hidden tradition, and that Yeats is a great guide to illuminate the quest and that Heaney is an inheritor or an achiever of the quest.This paper begins with the hypothesis that the modern Irish poetry is seeking their hidden tradition, 'uisneach'. I think that to understand the modern Irish poetry, we should first understand what is meant by 'uisneach'. 'Uisneach' has the various meanings: in the geographical sense, it means the area of the "territorially elusive" fifth province of Mide, the navel or the center of Ireland; in the religious sense, it means the sacred center of Ireland in pagan times; in the mythological sense, it is related to the Ulster Cycle including "Oidheadh Chloinne Uisneach", the fate of the Sons of Usnech, known as the Deirdri Ballads; and in the aesthetical sense, it means the origin where creative energy is flowing. W.B. Yeats was a knight in charge of the quest of the Irish political independence through the Celtic Revival against Anglo-Saxon's scientific modernity. His search for 'uisneach' reflects the resistance on the regional as well as the European level against Anglo-saxon's culture. Seamus Heaney's poetry is also going toward the fifth spiritual space where the Irish people believe a reconciliation is to be made, by taking some steps. And lastly, he also goes beyond the global space toward their hidden world based upon Celtic belief and the mild liberalist aestheticism. My last conclusion is that 'uisneach', a hidden tradition or vision means the Celtic vision modern Irish writers have sought. I think that Yeats is a poetic predictor or mentor to illuminate another waste land, Ireland, by suggesting the vision while Heaney is an inheritor in that he goes toward the hidden tradition Yeats suggested.