As early as 1842, in a series of letters to the Nonconformist newspaper on "The Proper Sphere of Government," he propounded a belief in human progress based on the modifiability of human nature through adaptation to its social surroundings, and he asserted the tendency of these social arrangements to assume of themselves a condition of stable equilibrium.

The nervous system, however, possesses the power of modifiability to a marked degree, even a single impression sufficing to make striking modification.