Originally I had a link to a chapter in one of Rossi's books. Then I recently came across a sixty page book that is available on his website. Here is the first paragraph in chapter two.
The earliest sources of psychotherapy and therapeutic hypnosis began almost 300 years ago with Anton Mesmer’s defense of his medical thesis Dissertatio Physico-Medica de Planetarum Influxu on May 27, 1766. This was the time of the Swiss philosopher, Jean-Jacques Rousseau (1712-1778), when there were philosophical clashes between the mechanistic and naturalistic views of human nature.
Rousseau believed humans experienced developmental stages and that the “exercise” of mental abilities facilitated the growth of the brain. Charles Bonnet (1720-1793), an experimental naturalist familiar with Rousseau’s views, proposed to the Italian scientist Michele Vincenzo Malacarne (1744-1816) that neurons could respond to exercise just as muscles do. Malacarne (1793, 1819) then carried out experiments with littermates of birds and dogs. He observed that those exposed to enriched environments and intensive training had larger brains!
This was the forerunner of modern neuroscience research documenting how novelty, exercise, training, and the voluntary focusing of attention can facilitate the growth and re-organization of neural networks of the brain. This is the foundation of our current conceptions of how gene expression and brain plasticity in psychotherapy, therapeutic hypnosis, and