Rousseau and Kant prepared the doctrine Schopenhauer first proclaimed pure.

Evidence

It was prepared by Rousseau and Kant, but was first proclaimed in its purity by Schopenhauer. For this reason, in spite of inconsistency and a certain shallowness, his philosophy has considerable importance as a stage in historical development. — Bertrand Russell, History of Western Philosophy, 2752

Categorization

• XREF: Frames the genealogy of will-primacy as Rousseau → Kant → Schopenhauer → Nietzsche et al. — connects to: Will-primacy doctrine, not pessimism, is Schopenhauer’s most influential legacy. — Bertrand Russell, History of Western Philosophy, 2752; Augustine anticipated both Descartes cogito and Kant time theories — Bertrand Russell, History of Western Philosophy, 1394; Horkheimer was a self-declared Marxist who favored Schopenhauer over Lukács and the interpretative school. — Rolf Wiggershaus, The Frankfurt School: Its History,…, 204 (+1 more)
• corroborated: 2 independent passages support this claim — Bertrand Russell, History of Western Philosophy, 2752

Broader Connections

• Augustine anticipated both Descartes cogito and Kant time theories #expands (0.65) — Bertrand Russell, History of Western Philosophy, 1394