Citizenship in a Republic is the title of a speech given by the former President of the United States, Theodore Roosevelt, at the Sorbonne in Paris, France on April 23, 1910.
One notable passage on page seven of the 35-page speech is referred to as “The Man in the Arena”:
It is not the critic who 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.
Someone who is heavily involved in a situation that requires courage, skill, or tenacity (as opposed to someone sitting on the sidelines and watching), is sometimes referred to as “the man in the arena”.