Precedent is solidified experience. In the realm of ideas it is canned goods.  
It is very useful when fresh ideas are not to be had.
 
There are advantages in doing things just because they always have been done. You know what will happen. When you do new things you do not know what will happen.
 
Success implies not only sound reasoning, but also the variable factor of how a thing will work, which is found out only by trying it.
 
Hence, the surest road to success is to use a mixture of precedent and initiative. Just how much of each you will require is a matter for your judgment.
 
19
To go entirely by precedent you become a mossback. You are safe, as a setting hen or a hiving bee is safe. Each succeeding generation acts the same way. There is a level of efficiency, but no progress.
 
Boards, trustees, and institutions lay great stress upon precedent, as they fear responsibility. To do as our predecessors did shifts the burden of blame a bit from our shoulders.
 
The precedent is the haven of refuge for them that fear to decide.
 
Courts of law follow precedent, on the general theory that experience is more just than individual decision.
 
Precedent, however, tends to carry forward the ignorance and injustice of the past.
 
Mankind is constantly learning, getting new views of truth, seeing new values in social justice. Precedent clogs this advance. 20 It fixes and perpetuates the wrongs of man as much as the rights of man.
 
Hence, while the many must trust to precedent, a few must always endeavor to break it, to make way for juster conclusions.
 
Precedent is the root, independent thinking is the branch of the human tree. Our decisions must conform to the sum of human experience, yet there must be also the fresh green leaf of present intelligence.
 
We cannot cut the root of the tree and expect it to live, neither can we lop off all the leafage of the tree and expect it to live.
 
The great jurist, such as Marshall, is one who not only knows what the law is, but what the law ought to be. That is, to his knowledge of precedent he adds his vision of right under present conditions.
 
Precedent is often the inertia of monstrous iniquity. War, for instance, is due 21 to the evil custom of nations who go on in the habit of war-preparedness. The problem of the twentieth century is to batter down this precedent by the blows of reason, to overturn it by an upheaval of humanity.
 
Evil precedent also lurks in social conditions, in business, and in all relations of human rights. The past constantly operates to enslave the present.
 
We must correct the errors of our fathers if we would enable our children to correct ours.
 
Our reverence for the past must be continually qualified by our reverence for the future.
 
We are on our way to the Golden Age. The momentum of what has been must be supplemented by the steam of original conviction, and guided by the intelligence and courage of the present.