96 PLINY'S NATURAL HISTORY. [P.ook XVIII. 



proprietors, whose avarice had now taught them to repent, 

 thinking it quite sufficient to have thus proved how easy it 

 was for him to acquire riches whenever he pleased. At a 

 more recent period, again, Sextius, 54 a Roman philosopher re- 

 siding at Athens, made a similar application of his knowledge. 

 Such, then, is the utility of science, the instruction provided 

 hy which it shall be my aim, as clearly and as perspicuously 

 as possible, to apply to the various occupations of a country 

 life. 



Most writers have said that it is the dew, scorched by a 

 burning sun, that is the cause of mildew 55 in corn, and of coal- 

 blight in the vine ; this, however, seems to me in a great 

 measure incorrect, and it is my opinion that all blights result 

 entirely from cold, and that the sun is productive of no injurious 

 effects whatever. This, in fact, will be quite evident, if only a 

 little attention is paid to the subject ; for we find that the blight 

 makes its appearance at first in the night time only, and before 

 the sun has shone with any vigour. The natural inference is, 

 that it depends entirely upon the moon, and more particularly 

 as such a calamity as this is never known -o happen except at the 

 moon's conjunction, or else at the full moon, periods at which 

 the influence of that heavenly body is at its greatest height. 

 For at both of these periods, as already 56 stated by us more 

 than once, the moon is in reality at the full ; though during 

 her conjunction she throws back to the heavens all the light 

 which she has received from the sun. The difference in the 

 effects produced by the moon at these two periods is very great, 

 though at the same time equally apparent ; for at the conjunc- 

 tion, that body is extremely hot in summer, but cold in win- 

 ter ; while, on the other hand, at the full moon, the nights are 

 cold in summer, but warm, in winter. The reason of this, 

 although Fabianus and the Greek writers adopt another me- 

 thod of explaining it, is quite evident. During the moon's 

 conjunction in summer, she must of necessity move along with 

 the sun in an orbit nearer to the earth, and so become warmed 



54 Mentioned by Seneca, Ep. 59. 



85 It was reserved for the latter part of the last century to discover that 

 mildew operated on vegetation through the medium of minute, parasitical 

 fungi. It is mostly attributed to defects in the light or the atmosphere, 

 or else humidity in excess. See c. 44 of this Book. 



55 In B. ii. e. 6, for instance. 



