182 THE PRINCIPLES OF 



certain number of years it ceases to be profitably productive. 

 This we know to be the case when a new country is settled 

 or occupied by immigrants, and when their fields become 

 exhausted they shift their tent further westward or eastward, 

 as the case may be. They forsake the fields which are no 

 longer profitable, and they break new or, as it is sometimes 

 called, virgin soil. In process of time the ground which has 

 been forsaken, or which has ceased to be profitable, regains 

 its fertility in a great measure, and that being the case it 

 may be again tilled, and once more subjected to a series of 

 croppings, which in time again reduce it to a state in which 

 it is unprofitable, and then there is a period of rest and 

 neglect ; so that we have at once a kind of rough and natural 

 rotation of crops oscillating between a period of cropping and 

 a period of rest or neglect. Such a state of things is still 

 extant upon the northern coasts of Scotland. I hear also 

 that it is not uncommon in Norway and Sweden, and I 

 know from personal observation that in Northumberland 

 fields have, even in recent years, been cultivated in this way, 

 cropped as long as they would crop to a profit with wheat or 

 corn, and then allowed to fall away into grazing-ground simply 

 by the invasion of grass and weeds which take possession of 

 the ground. They are then grazed by cattle, and after a few 

 years the land becomes once more capable of bearing a series 

 of crops. That is a rotation in a sense. A period of rest has 

 always been recognized as necessary for land ; provision is 

 made for it in the Levitical Law. The Jewish ordinance was 

 that land should be fallowed, or rested, every seven years, 

 and the land was then said to enjoy her Sabbath. 



The reasons why land is thus able to recoup itself have 

 occupied our attention previously. It is- sufficient, I think, 

 to remind you that those natural forces originally producing 

 the decay and crumbling down of rocks are still in action, and 

 that when we speak of land recovering its energies by rest we 



