In the final book, Kames turns to an account of progress in the sciences of logic, morals, and theology. He seeks to vindicate the claim that “human understanding is in a progress towards maturity, however slow.” Throughout the entire work, Kames expounds on his fundamental hypothesis that at the beginning of the history of the human race, savagery was ubiquitous and that the human story is one of an emergence out of barbarism and toward maturity.
"Human Actions analysed.
The hand of God is no where more visible, than in the nice adjustment of our internal frame to our situation in this world. An animal is endued with a power of self-motion; and in performing animal functions, requires no external aid. This in particular is the case of man, the noblest of terrestrial beings. His heart beats, his blood circulates, his stomach digests, &c. &c. By what means? Not surely by the laws of mechanism, which are far from being adequate to such operations. They are effects of an internal power, bestow’d on man for preserving life. The power is exerted uniformly, and without interruption, independent of will, and without consciousness.
Man is a being susceptible of pleasure and pain: these generate desire to attain what is agreeable, and to shun what is disagreeable; and he is possessed of other powers which enable him to gratify his desires. One power, termed instinct, is exerted indeed with consciousness; but without will, and consequently without desiring or intending to produce any effect. Brute animals act for the most part by instinct: hunger prompts them to eat, and cold to take shelter; knowingly indeed, but without exerting any act of will, and without foresight of what will happen. Infants of the human species are, like brutes, governed by instinct: they apply to the nipple, without knowing that sucking will satisfy their hunger; and they weep when pained, without any view of relief.1 But men commonly are governed by desire and intention. In the progress from infancy to maturity, the mind opens to objects without end, agreeable and disagreeable, which raise in us a desire to attain the former and avoid the latter. The will is influenced by desire; and the actions thus performed are termed voluntary."
Henry Home, Lord Kames
Henry Home, Lord Kames (1696–1782), one of the leaders of the Scottish Enlightenment, was a judge in the supreme courts of Scotland and wrote extensively on morals, religion, education, aesthetics, history, political economy, and law, including natural law. His most distinctive contribution came through his works on the nature of law, where he sought to combine a philosophical approach with an empirical history of legal evolution.