The word homily is derived from the Greek word homilia (from homilein), which means to have communion or hold intercourse with a person. In this sense homilia is used in I Cor., xv, 33. In Luke, xxiv, 14, we find the word homiloun, and in Acts, xxiv, 26, homilei, both used in the sense of "speaking with". In Acts, xx, 11, we meet the term homilesas; here it is used, for the first time, to signify a sermon to the Christians in connexion with the breaking of bread: it was evidently an informal discourse, or exposition of doctrine, for we are told that St. Paul "talked a long time . . . until daylight". Thereafter the word was used as a sign of Christian worship (Justin, "Apol. I", c. lxvii; Ignatius, "Ep. ad Polyc.", v). Origen was the first to distinguish between logos (sermo) and homilia (tractatus). Since Origen's time homily has meant, and still means, a commentary, without formal introduction, division, or conclusion, on some part of Sacred Scripture, the aim being to explain the literal, and evolve the spiritual, meaning of the Sacred Text. The latter, as a rule, is the more important; but if, as in the case of Origen, more attention be paid to the former, the homily will be called expository rather than moral or hortatory. It is the oldest form of preaching. Christ himself may be said, but with a difference to be noted later, to have preached in this style (cf. Luke, iv, 16-20). It was the kind of preaching that was used by the Apostles and Fathers in addressing the faithful. In the "First Apology" of Justin Martyr (c. lxvii) we read: "On the day called Sunday, all assembled in the same place, where the memorials [apomnemoneumata] of the Apostles and Prophets were read . . . and when the reader has finished, the bishop delivers a sermon", etc. In this connexion, the "Encyclopaedia Britannica" (ninth edition) says: "The custom of delivering expositions or comments more or less extemporaneous on the lessons of the day at all events passed over soon and readily into the Christian Church" [i.e., from the Jewish synagogue]. From this the Catholic view differs, and maintains that the kind of homily referred to by Justin was not a continuation of the Jewish commentary on Scripture, but was an essential part of Christian worship, a continuation of the Apostolic sermon, in fulfilment of Christ's commission to His disciples. Both indeed had an external similarity (see Luke, iv, 16-20), but in essence one differed from the other as much as the Christian religion differed from the Jewish.

The oldest homily extant is the so-called Second Epistle of Clement to the Corinthians; it is now generally admitted, however, that it is not by Clement (see Bardenhewer, "Patrologie", tr. Shahan, p. 29). We have a hundred and ninety-six by Origen; some from St. Athanasius, although he was more of a controversialist than a homilist; the brief and antithetic homilies of St. Leo the Great have also come down to us; and the more important ones of St. Gregory the Great. Also well-known homilists are: Hilary, Ambrose, Chrysostom, Jerome, Augustine, Fulgentius, Isidore, Bede, Bernard of Clairvaux; and there are many others. Even after the art of rhetoric was brought to bear on preaching, the homiletic form continued, so that there were recognized two styles of preaching, the extempore, unpolished, or familiar, and the polished, or carefully prepared, style. Fine examples of both may be seen in St. Chrysostom; also in St. Augustine, who, in referring to his homiletic preaching, said that he humbled himself that Christ might be exalted. The homiletic was the favourite style of preaching during the Middle Ages; and many of the sermons then preached might, from the frequent use of the Sacred Text, be called Scriptural mosaics (see Neale, "Mediaeval Sermons").

At present there are four recognized ways of treating the homily, but not all to be equally commended.

The first method consists in treating separately each sentence of the Gospel. This was the uniform method of St. Anselm, as we gather from the sixteen sermons that have come down to us. It is not to be recommended, for it gives, at best, but a fragmentary and scattered treatment.

The second method is quite the opposite; it focuses the entire content of the Gospel in a single idea. It is usually called the "higher homily", and differs from the formal or set sermon only in the absence of introduction and peroration. It is clear that only certain Gospels can be treated in this way.

The third kind selects some virtue or vice arising out of the Gospel, and treats one or the other to the exclusion of all else. This kind of homily is commonly called a "prone".

The fourth kind is that which first paraphrases and explains the entire Gospel, and then makes an application of it. This, the method of St. Chrysostom, seems, except where the "higher homily" applies, to be the best, because it can guard against the besetting defect of the homily, namely, a tendency to lack of unity and continuity.

The advantages of the homily are that it is a form of preaching which was in use from the very beginning of Christianity; it is simple and easily understood; it affords a better opportunity than the formal sermon for interweaving Sacred Scripture. The most appropriate time for the homily is at the early Mass; for the formal sermon, at the principal Mass; and for the catechetical sermon (see ), at the evening devotions. As to its place in the Mass, the homily is usually preached after the first Gospel; but St. Francis de Sales would prefer that it come after the Communion, and in his letter to the Archbishop of Bourges he quotes the words of St. Chrysostom: "Quam os illud quod SS. Mysteria suscepit, daemonibus terrible est"; also those of St. Paul (II Cor., xiii, 3): "in experimentum quaeritis ejus, qui in me loquitur Christus."

For Clementine Homilies, see .

KEPPLER in "Kirchenlex.", s.v. "Homiletik"; DUCHESNE, "Christian Worship" (tr. St. Louis, 1908); SCHMID, "Manual of Patrology" (St. Louis, 1899); THOMASSIN, "Vetus et Nova Ecclesiae Doctrina" (Paris, 1688); DIGBY, "Mores Catholici" (London, 1846); NEALE, "Mediaeval Sermons" (London, 1856); MACNAMARA, "Sacred Rhetoric" (Dublin, 1882); POTTER, "Sacred Eloquence" (New York, 1891); SCHUECH, "The Priest in the Pulpit" (tr. New York, 1905); HAMON, "Traite de la Predication" (Paris, 1906); MOURRET, "Lecons sur l'art de precher" (Paris, 1909). BARDENHEWER, "Patrology", tr. SHAHAN (St. Louis, 1908): See bibliography of .

P. A. Beecher.