We have few indications of date, or of mutual relations between the three Dialogues. I is based upon the author’s recollection of a conversation which took place ‘a long time ago’, about A. D. 66, the date of Nero’s visit to Greece. A principal speaker is Ammonius the Peripatetic philosopher of Lamprae, Plutarch’s instructor, who also speaks, with the same authority, in III. In II, Serapion, the Athenian poet, to whom the collection is dedicated in I, takes a leading part. Theon, a literary friend, who appears frequently in the _Symposiacs_ and in the _Face in the Moon_ comes into I and II. An interesting person is Demetrius of Tarsus, another literary friend, who, in III, has just returned from Britain, and who has been probably identified with ‘Demetrius the Scribe’, named on two bronze tablets found at York, and now in the York Museum (see _Hermes_, vol. 46, p. 156). The year of Callistratus at Delphi, which marks the date of III, is conjecturally fixed as A. D. 83-4 (see Pontow in _Philologus_ for 1895, and cp. _Sympos._ vii. 5). As Agricola’s term of office ended in A. D. 84 or 85, Demetrius may have served under him. The general tranquillity of the world depicted in III hardly gives us much to build upon. In I Plutarch and his brother Lamprias are both speakers. Lamprias appears in his usual character, a good companion, light-hearted and reckless; Plutarch speaks gravely and at length, and the debate is closed by Ammonius. In III Lamprias, Plutarch not being named, speaks gravely throughout, and, on the suggestion of Ammonius, closes the debate. In II, neither brother is named, and the last speaker is Theon. In the Symposiac Dialogues one or other brother is usually present, sometimes both. In the _Face in the Moon_ Lamprias alone takes part, and he acts as moderator. It is not easy to interpret these facts. M. Gréard concludes that Lamprias died early. If so, was the name, which was borne by the grandfather and by one of the sons, transferred, for literary purposes, to Plutarch himself? M. Chenevière, in his pleasant essay on Plutarch’s friends (a Latin prize dissertation) suggests that, under whatever name, the leading speaker always conveys Plutarch’s own views. Certain topics recur in this series of Dialogues. Thus the problem as to the meaning of the E at Delphi, which is the main subject of I, is glanced at, with some impatience, by Philippus the historian in III. The identification of Apollo with the sun, dismissed at the end of I as a mere beautiful fancy, is questioned again in III and allowed to stand over as unsettled. It is touched upon in II, c. 12. The hypothesis of a plurality of worlds, brought forward by Plutarch in I. c. 11, with special reference to the views of Plato in the _Timaeus_, reappears, again in connexion with the five regular solids, in III. It may be noticed that Plutarch was not, at the date of the conversation narrated in I, a priest of the temple (see c. 16).