(1) c. 1, 920 B. The opening of the Dialogue is abrupt; compare that of ‘On the Instances of Delay in Divine Punishment’. Many of the Symposiacs open as abruptly, and there a former conversation is sometimes resumed by the same speakers. It seems not impossible that there had been a previous Dialogue on the Face in the Moon, and, again, that the περὶ ψυχῆς preceded the _De Sera numinum Vindicta_. Wyttenbach reads τῷ γ᾽ ἐμῷ for the MSS. τῷ γὰρ ἐμῷ, but suggests τῷ παρ᾽ ἐμοί, which seems better. Sylla is not the author, but the depository, of the myth. For εἰ δεῖ τι ... προσανακρούσασθαι he reads εἰ δή τι ... προσανεκρούσασθε. The past indicative is required by the τί δὲ οὐκ ἐμέλλομεν which follows, the reference being to the previous discussion (see Introduction). The combination εἰ δή or εἰ δή τι is a frequent one. If δή was altered to δεῖ, the further alteration of the verb would follow. Sylla’s language is nautical, as in c. 26, ‘Did you really stop rowing, and back-water on to the received views?’ (2) c. 3. 921 A. _For our sight._ ὄψις is an old correction for ἴτυς of the MSS., and is required by the context. (3) c. 4. 921 C. _Equal in breadth and length._ Empedocles (Fr. 17, 20) has a line καὶ Φιλότης ἐν τοῖσιν, ἴση μῆκός τε πλάτος τε. This poetical quotation is introduced to indicate that the world is not a mere point, but has sensible dimensions. In literal truth, the habitable world was held to be twice as long as it was wide (i. e. N. to S.). The words as to the earth occupying ‘a point central to the sphere (i. e. orbit) of the moon’ are quoted from the Second Hypothesis of Aristarchus (see Introduction). It has been proposed (by Dr. Max Adler) to substitute the name of Clearchus for that of Hipparchus. But the quarrel of Lamprias is not with philosophers but with astronomers and mathematicians, represented by Apollonides and Menelaus. The greatest of them is of absolute authority as to angles of reflexion, &c., not so when he propounds a physical theory of vision, which many find unsatisfactory. For the theory itself see the quasi-Plutarchean _De Placitis_, 4, 13. For the words καίτοι γε φίλε πρίαμ᾽ (omitted in the translation), Turnebus proposed καίτοι γε φίλε Λαμπρία, which is very attractive as to the letters, but impossible, unless the text be wholly reconstructed, because Lamprias is himself the speaker. For discrepancies between the mathematically correct theory of reflexion and its physical application see chapters 17 and 23. (4) c. 7, 924 B. _That segments of beams...._ The sense intended by the translation is this: A beam is sawn into two segments on the earth’s surface. The two segments, which at first are separated by a short interval, move simultaneously towards the earth’s centre, but in converging, not parallel, lines, and jam each other long before they reach it. (This is suggested by Aristotle, _de Caelo_, 2, 14, 296 b 18.)