He viewed extant manuscripts as comprising three families, or recensions, the Byzantine, the Western, and the Alexandrian, giving preference to readings in the latter.

If certain manuscripts had a common ancestor manuscript, perhaps came from a particular revision of early texts, or were produced in a particular area, they would probably have at least some variations in common, and hence they are said to belong to the same family, or group. On the basis of similarity in such differences, scholars have sought to classify the texts into groups, or families, the number of which has increased with the passing of time, till reference is now made to the Alexandrian, Western, Eastern (Syriac and Caesarean), and the Byzantine texts, represented in various manuscripts or in different readings scattered throughout numerous manuscripts.