Typology was all pervasive in the medieval period. It influenced art, history, literature, and philosophy. Yet until this study there existed no Medieval or Patristic guides to typology available to the English reader. This study was undertaken to fill that gap. The central portion of this thesis was a translation from Medieval Latin into Modern English of an early Medieval guide to typology: Isidore of Seville's Allegoriae Quaedam Sacrae Scripturae. Research necessitated an examination of the ostensible Patristic sources upon which Isidore drew. Evidence suggested that Isidore was likely indebted most heavily to the writings of St. Augustine of Hippo and St. Ambrose of Milan. Research concluded that, although the Allegoriae was originally intended for clerics, it would be useful today primarily as a guide to the understanding of Medieval aesthetics. The translation and commentary were prepared in such a way as to be useful to Medievalists, whether they be concerned with art, history, literature, or philosophy.