AMBROSIUS AURELIUS THEODORUS, an ancient Latin writer, lived about the beginning of the fifth century. In the preface to his Saturnalia he tells us that Latin is not his mother tongue; and from the Græcisms that abound in his style, we infer that he was a Greek. The opinion that he was a Christian rests on no sure basis, and is rendered doubtful by the warm sympathy which is lavished in the work above mentioned on the sanctity and religious opinions of the heathen priest Prætextatus. He had a son, Eustathius, to whom he addressed the introduction to his Saturnalia. Nothing more is known respecting him. Only three of the works of Macrobius are extant. His grammatical treatise De Differentiis et Societatibus Graeci Latiniique Verbi, is known to us merely under the form of an abstract by a certain author, Joannes. In his Commentarius ex Cicerone in Somnum Scipionis he discourses on the tenets of the later Platonists touching the constitution of the universe. His principal work, Saturniorum Conversiorum Libri VII., is a collection of heterogeneous discussions on the Saturnalia and the Roman deities, on jesting and feasting, on the poetry of Virgil, and on the physiology of the human frame. The best editions of Macrobius are those of Gronovius, 8vo, Leyden, 1670; and the Bipont, 2 vols., 1788.