BOOK XVir. III. 27-30 



or a light soil be detected bv a standard of weight, 

 for what can be understood to be the standard weight 

 of earth ? Nor is alluvial soil deposited by rivers 

 always to be recommended, seeing that some plants 

 do not flourish in a damp situation ; nor does that 

 much praised alluvial soil prove in experience to be 

 beneficial for a longperiod,except for a willow. One of 

 the signs of a good soil is the thickness of the stalk in 

 corn, which incidentally in the famous Leborine plain 

 in Campania is so large that they use it as a substitute 

 for wood ; but this cuiss of soil is every where hard to 

 work, and owing to this difliculty of cultivation puts 

 ahnost a heavier burden on the farmcr because of its 

 merits than it could possibly inflict by reason of 

 defects. Also the soil designated glo^\ing-coal earth " 

 appears to be improved bv marl ; and in fact tufa of a 

 pliable consistency is actually hcld by the authorities to 

 be a desideratum. For vines Virgil actually does not 

 disapprove of a soil in which ferns grow ; and many fg^"* ' 

 plants are improved by being entrusted to salt land, 

 as they are better protected against damage from 

 creatures breeding in the ground. Ilillsides are not 

 denuded of their soil bv cuUivation if the digging is 

 done skilfully, and not all level ground gets less than 

 the necessary amount of sun and air; and some 

 varieties of vine, as we have said, draw nourishment xiv. 23. 

 from frosts and clouds. AU matters contain some 

 deeply hidden mysterics, which each pcrson must use 

 his own intelligence to penetrate. What of the fact 

 that changes often occur cven in things that have been 

 investigated and ascertained long ago? In the 

 district of Larisa in Thessaly the emptying of a lake 

 has lowered the temperature of the district, and olives 

 which used to grow there before have disappeared, 



