Paul Tillich aims, as his theological and philosophical task, at reinterpreting the message of Christian faith in order to lead our contemporaries to understand its meaning. He asserts that the symbols used in the Christian message, which are not identical with the reality they point to, must never be taken literally. Christian symbols are words that mean various qualities of the basic reality, so that they should be interiireted by making use of philosophical concepts. By translating Biblical personalistic categories into ontological concepts, he seeks to integrate the personalistic and the ontological view of God. In addition to this theological characteristic, his ethics has its proper subject matter. In his ethical writings, he attempts to "remove the obsolete conflict between reason-determined ethics and faith-determined ethics," by showing that the religious principles dwell within the principles of moral action. He argues that it is impossible to drive a moral imperative from other sources than our own intrinsic nature which is our essential being. Thus, it is very difficult for him to develop ethics which deals with the question as to how life is to be governed in relation to external norms of human conduct.