Before Trump, before Brexit, before algorithms learned to feed our tribal instincts, a British surgeon named Wilfred Trotter mapped the psychology of the crowd. Written in the trenches of 1916, this slim, ferocious book asks a question we still haven't answered: why do human beings surrender their individuality to the group, and what happens when that instinct is weaponized? Trotter builds on Gustave Le Bon to argue that gregariousness - the deep biological pull toward belonging - shapes our decisions far more than reason. In wartime, national morale becomes a matter of life and death; in peace, it determines whether societies flourish or fracture. The book offers a systematic, even clinical, examination of how social habits and collective sentiment drive behavior. One hundred years later, it reads less like a historical artifact and more like a manual for understanding our current moment. Essential for anyone trying to make sense of propaganda, polarization, and the ancient, dangerous pull of us-versus-them.
