62 THE BOOK OF FORESTRY 
While the increase in lumber values which is bound 
to occur may cause the use of substitutes to some degree 
it is safe to say that wood in the future as in the past 
will be indispensable to our civilization, for it is hard 
to conceive of any substance, natural or artificial, which 
is so easily produced, so readily worked into shape and 
so generally useful as wood. 
