Because the "Will" is never satisfied, life is inherently suffering.
His argument that the present moment is fleeting and life is a "constant transition from desire to boredom." Schopenhauer-Handbuch: Leben — Werk — Wirkung
Called Schopenhauer his "great teacher," though he later rejected Schopenhauer’s "denial of life." Because the "Will" is never satisfied, life is
The collection of essays and aphorisms that finally made him a household name, containing his witty (and often cynical) advice on life. Philosophy & Psychology: Because the "Will" is never satisfied
The only true basis for morality is recognizing that other beings suffer from the same "Will" as you.