443 PLINY'S KA.TCEAL HISTORY [Book XVII. 



which is naturally rough and friable, we find recommended 

 by some authors. Virgil, 40 too, does not condemn for the viue 

 a soil which produces fern : 41 while a salted earth 42 is thought 

 to be much better entrusted with the growth of vegetation than 

 any other, from the fact of its being comparatively safe from 

 noxious insects breeding there. Declivities, too, are far from 

 unproductive, if a person only knows how to dig them pro- 

 perly ; and it is not all 43 champaign spots that are less acces- 

 sible to the sun and wind than is necessary for their benefit. 

 We have already 44 alluded to the fact, that there are certain 

 vines which find nutriment in hoar frosts and fogs. 



In every subject there are certain deep and recondite 

 secrets, which, it is left to the intelligence of each to penetrate. 

 Do we not, for instance, find it the fact, that soils which have 

 long offered opportunities for a sound judgment being formed on 

 their qualities have become totally altered ? In the vicinity 

 of Larissa, in Thessaly, a lake was drained ; 45 and the conse- 

 quence was, that the district became much colder, and the 

 olive-trees which had formerly borne fruit now ceased to bear. 

 When a channel was cut for the Hebrus, near the town of 

 ^nos, the place was sensible of its nearer approach, in finding 

 its vines frost-bitten, a thing that had never happened before ; 

 in the vicinity, too, of Philippi, the country having been 

 drained for cultivation, the nature of the climate became en- 

 tirely altered. In the territory of Syracuse, a husbandman, 

 who was a stranger to the place, cleared the soil of all the 

 stones, and the consequence was, that he lost his crops from 

 the accumulation of mud ; so that at last he was obliged to 

 carry the stones back again. In Syria again, the plough- 



what similar in nature to marl, and that though unproductive by itself, it 

 is beneficial when mixed with vegetable earth. Tufa and marl appear to 

 have been often confounded by the ancient writers. 



40 Georg. ii. 189. 



41 The Pteris aquilina of the modern botanists. 



42 Marine salt, or sub-hydrochlorate of soda, Fee thinks, is here alluded 

 to. It is still used with varied success in some parts of the west of 



France. 



43 Hardouin says, that he here alludes to the proverbial saymg among 

 the ancients, "Perflare altissima ventos"— " The winds blow only on the 

 most elevated ground." ** In B. xiv. cc. 4 and 12. 



« « Emisso." Fee would appear to think that the lake suddenly made its 

 appearance, after an earthquake, and from the context he would appear to 

 be right. These accounts are all of them borrowed from Theophrastus. 



