■i- t 
32 POLITICAL ECONOMY 
The long-period result may be overlaid, so 
to speak, as the surface of the sea is by 
waves ; but even when storm waves make 
the ocean a tumult tides still rise and fall. 
Finally, it is to be remarked that the 
tendencies to be studied are measurable, and, 
indeed, are actually measured in the course 
of our every-day doings, in terms of money. 
Owing to this, more precise generalisations 
can be laid down than would be possible 
otherwise.