Historically, walls have been constructed by those inside to prevent outsiders from getting inside the walls.
In the case of knowledge and the pursuit of truth, it is the reverse.
The wall which divides the knowledged from the uninformed has been constructed by those on the outside and the building blocks of this wall are opinions! Opinions separate the uninformed from the villages of knowledge.
“Once a person develops an opinion, it changes how they perceive their world” .
The wall of uninformed opinion completely distorts the reality of the professional’s current information and judgement. These precious tools, like surgical instruments, must be reexamined and sterilised every day.
Professionals never “have-it-made” Professionals are lifetime students who rehearse continually.
Those who are seduced by opinions become “roadkill” in the arena.
“It is not the critic that counts, not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood; who strives valiantly; who errs, who comes short again and again, because there is no effort without error and shortcoming; but who does actually strive to do the deeds; who knows great enthusiasms, the great devotions; who spends himself in a worthy cause; who at the best knows in the end the triumph of high achievement, and who at the worst, if he fails, at least fails while daring greatly, so that his place shall never be with those cold and timid souls who neither know victory nor defeat.” 
Put down your opinion shields and study every day. There is no intellectual free lunch.
Truth is not an opinion.
Charles Clanton Rogers February 3, 2016
 “The 3 essential principles of the Zen mind.”
 Theodore Roosevelt, THE MAN IN THE ARENA
Excerpt from the speech “Citizenship In A Republic”
delivered at the Sorbonne, in Paris, France on 23 April, 1910