In this way he has gone over a great portion of the field of physics, and in many cases has either said the last word for the time being, or else started new and fruitful developments.
A well-nigh ubiquitous system of espionage, perhaps most fruitful when directed against official corruption, sapped the foundations of public confidence.
" The wealth they brought into the country, and their fruitful commercial activity, especially in the colonial trade, soon revealed them as an indispensable element of the prosperity of the city.
Experience with epidemics, dearly bought in the past, has shown that one fruitful cause is the laying open to the inroads of some Fungus or insect, hitherto leading a quiet endemic life in the fields and forests, large tracts of its special food, along which it may range rampant without check to its dispersal, nutrition and reproduction.
This fruitful region, however, was covered with villages till the frightful devastations of the 18th century; and even now it is, comparatively speaking, well cultivated.