The majority of the essays are from the time of World War I and the immediate aftermath; Hesse's thought changes profoundly at the time, as was true of many. The first essay takes it title from the beginning of the Ode to Joy section of Beethoven's Ninth, "O Freunde, nicht diese Töne." O friends, not these sounds. Beethoven turns to the exhilaration of Schiller's Ode To Joy; Hesse just asks that his fellow intellectuals not spew hatred of their enemy, that if a war must be fought, it can be done without contempt for those whom just six months ago you admired. This essay, which appeared in the Zurich newspaper, and not in Hesse's homeland of Germany, spurred Rolland to write to Hesse. The opening essays of Rolland's Above The Battle try to make the same point.
Well. A difficult proposition. Not the least risk of war is its need to dehumanize the enemy.
The next several essays document Hesse's growing disenchantment with the war. But it's the essays of 1919 I found especially interesting, the key one being "Zarathustra's Return." As you might guess, Nietzsche is the central influence here. But what Hesse gets from Nietzsche is not what you might expect, and certainly not what Nietzsche's sister and her fellow Nazis would have wanted you to get. Rather Hesse draws from Nietzsche's insistence that we not succumb to herd mentality the idea we should be pacifist, that we should withdraw from society; if society wants the individual to follow blindly into mass mobilization, then perhaps a Nietzschean refusal leads to pacifism.
Years ago now when I read those novels of Hesse I did read, I was put off a bit by the implied argument of many of them, that we disengage from the world; the Glass Bead Game was my favorite at the time for what were philosophical reasons, the fact that Knecht leaves the academy to once again engage with the world at the end. Hesse withdrew from the world to live on his Swiss mountain, and his books often argue that philosophy. But reading this made that decision, for me, if not defensible, at least understandable.
The last few essays were less interesting and are mostly around the period of World War II. It also includes his brief Message to the Nobel Prize Banquet of 1946.
A fascinating book, and crucial to understanding Hesse's novels, I think, and to the post World War I mindset.