Eliot`s use of the term "tradition" in "Tradition and the Individual Talent" published in 1919 has aroused a lot of confusion and discussion. Apparently it seems to have changed its concept radically and fundamentally, but the truth is not that. The reason why it is misunderstood so widely can be summarized as follows. First, Eliot didn`t define the concept of the term clearly. Second, the publication of his conversion to Anglo-Catholicism and conservatism is a shock to the readers who are not willing to accept the fact that the concept of the "tradition" is under change and development. Third, the discussions and presentations of the concept of the "tradition" are fragmentary and unsystematic. Last, the use of the term has been enlarged a lot from the criterion of the literary works to the criterion of ethics, morality, philosophy, way of life, and religion etc. In this paper, I examined the background which contributed to the formation of the concept of the term "tradition". As is well known he was born and bred in a Unitarian family. Unitarianism emphasizes individuality and individual divineness. Eliot, therefore, could not find any external standard to evaluate literature in Unitarianism. He was forced to establish a criterion or standard to evaluate a work of literature by himself. It seems natural that Eliot was attracted to Bradley`s monism. In Bradley`s philosophy, appearance and reality are not different from each other, and they are only different aspects of one reality. This kind of view is the same as that of Buddhism which Eliot studied in the Graduate School, and before and after that period. Eliot presented the "tradition" as the external criterion of literature. Eliot`s tradition is an organic whole which consists of all the literature created in Europe from ancient times to modern. In short, a work of literature can be thought in the relationship with other works. Eliot`s tradition emphasizes the relationship between the literary works. This view of relatedness is inherited from Bradley`s philosophy and Buddhism. After his conversion to Anglo-Catholicism, Eliot values the "orthodox" high and the view of "orthodox" is closely related with the concept of tradition and sometimes they are interchangeable. When Eliot proposed the "tradition" first, it was thought mainly as the criterion of literature, but after years went by, it was thought as the criterion of morality, ethics, philosophy and religion etc. This development/enlargement was the comprehensive and complex result of the Unitarianism, Bradley`s philosophy, Indian thoughts including Buddhism, and Anglo-Catholicism.