Of authority or an office, or someone holding it) superior to all others.
"a unified force with a supreme commander"
synonyms: highest-ranking, chief, head, top, foremost, principal, superior, premier, first, prime;
The answer is: the book will bear witness to events that must be known.
"Night" is an autobiographical novel by Elie Wiesel, who accounts his struggle as a prisoner during the Holocaust. He desires to make sure the world acknowledges what happened in concentration camps as he narrates how crude society was and how inhuman even prisoners became towards one another - mostly attemping to survive themselves.
The first-aider will be ready with a first aid kit and will be on guard in case of accidents or injuries. First aid means, the first action done on someone who is injured or not feeling well within the designated place. He/she must know some first aid treatments or methods, such as treating a cut or bruise, giving artificial ventilation and CPR, etc.