This study approaches "virtus "as a moral value concept. The author argues that it is only through conceptual analysis that the meaning and value of" virtus "are given adequate illustration, and that philology should be regarded as a part of practical philosophy. The study covers Roman literature from the beginnings until Livy. During the Roman Republican Age, "virtus "was considered a man's contribution to his society and state, in terms of collectivism. "Virtus "('manliness') was thought to be more real than any of its particular and transitory representations, i.e. individual male citizens. On the other hand, as an existentialist value concept, "virtus "at a relatively early stage denoted a man's intrinsic or ontic value or his true self, without regard to any worldly success whatsoever. The final analysis shows that "virtus "('virtue') is congruous with or even synonymous to individualism. This book also presents a contribution to gender studies from the standpoint of a man.