ON HARNESSING HEREDITY 
If new habits are hard to start, new trails are 
harder. It is hard to teach a plant to twine when 
it has never twined before, or to persuade it to 
be pink when it has always been yellow; just as 
it is hard to get a boy interested in the study of 
law when his likes, all his life, have been along 
the lines of engineering or mechanics. 
In the establishment of a new trait, in fact, 
the whole motion of life must be interrupted, its 
momentum arrested, the resulting inertia over- 
come, and new momentum in a new direction 
gained. 
But, if every difficulty has its recompense, we 
are well repaid for the labor of acquiring or 
instilling a new trait by the fact that, once 
acquired, it has a tendency of its own to increase 
and expand and grow. 
The boy who finally gets interested in law, who 
gets past the point where it becomes an irksome 
drudgery, begins, at length, to develop a steadfast 
love for his work so that what was to him, once, a 
bug-bear at last becomes an absorbing ideal. 
The cactus, for example, which produced its 
first spines with difficulty, now gets more and 
more spiny, although the need for spines has 
disappeared. Our flowers grow more beautiful, 
our fruits more luscious as their tendencies gain 
momentum. 
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