Paul Sollier (1861–1933) at the time was considered the most gifted pupil of French neurologist Jean-Martin Charcot, together with Joseph Babinski.

Because of his interest in psychology, unique at the time for a neurologist, but also his opposition to the leading figure in psychiatry Pierre Janet, Sollier was never accepted by his contemporary neurologists and psychiatrists.

He could not follow an academic career and was never elected to the Académie de Médecine, despite several applications.

His scientific and clinical interests encompassed classical neurological syndromes but also hysteria, memory, emotions and mental retardation, where he was the precursor of the development of the intellectual ratio.

Already in the 1890s, he developed cognitive behavioral therapies, which he applied to his most famous patient, French novelist Marcel Proust.