The purpose of this volume is to trace the history of the medieval Latin hymn from the point of view of usage. It must be evident to any student of a subject which is spread over a thousand years of human experience in the widening environment of an entire continent that a guiding thread is needed to show the way. One must not, at the same time, ignore the fact that a monumental religious literature in the poetic field is involved. But the hymn is functional, having its greatest significance as a lyric when employed in an act of worship. Latin hymnology, moreover, is an aspect of ecclesiastical studies following the history of the Church through the classical and medieval ages into modern times. A wider cultural background than the immediate interest of theology and religion is reflected in the hymns of any age. Here often lie secrets of interpretation which make possible an appreciation of contemporary thought. As the study of the medieval hymn is followed from the standpoint of life and usage, the antiquarian and the literary critic, who cannot fully satisfy the quest of the student for reality, must give place to the medieval worshiper himself who has revealed in its entirety each successive phase of a hymnological history not yet ended.