The meaning of the passage in question is, that the Æneadæ row up the river among the green woods, or (literally) "secant silvas," _travel the woods_, "placido æquore," _on the calm surface of the water_, _i. e._ by rowing up the placid stream of the river. This, and not that assigned by Servius following Terentienus, is the true meaning. 1st. Because _secare_ with the objective case means constantly in Virgil to _travel along_. Compare "viam secat ad naves," _Æn._ vi. 902.; "secuit sub nubibus arcum," v. 658., &c. 2ndly. Because the Tiber is described only as _placid_, not as _clear_; and as appears from _Æn._ vii. 31., was actually _very muddy_, "multa flavus arena." The immediately preceding words, "variisque teguntur arboribus," have been pronounced by a very learned critic (one who has often deserved well of Virgil) to be _idle, otiosa_. (See Wagner ad _Æn._ i. 678.) And his opinion has been sanctioned by the usually judicious Forbiger. But they are not idle; on the contrary, they are necessary to convey the idea that the Æneadæ passed up the river _under the shade of the trees_; and so are supplemental to the statement contained in the words cited by your correspondent, which inform us only that they went up the river. Hence a confirmation of the correctness of the received interpretation.
Your correspondent ERYX wishes to know, whether in the passage (_Æneid_, viii. 96.)--
"Viridesque secant placido æquore silvas,"
the word _secant_ can legitimately convey the same idea that is expressed in Tennyson's lines--
---- "my shallop ... clove The citron shadows in the blue."
There can be little doubt that this well-known passage in the _Æneid_ is the _original_ of Tennyson's image; that, in fact, it is an excusable plagiarism on the part of the latter, who, in introducing, his image, has, I think, missed the appropriateness, and therefore increased beauty, belonging to it in the original passage of Virgil.
When Æneas is journeying up the Tiber to visit Evander, the river, in order to lessen his labours--
but notwithstanding this, the journey was arduous as is shown in the _whole_ of the three lines 94-96.
"Olli remigio noctemque diemque fatigant, Et longos superant flexes, variisque teguntur Arboribus, viridesque secant pacido æquore silvas."