Adam Smith (1723-1790) was a Scottish moral philosopher and pioneering political economist and one of the key figures of the intellectual movement known as the Scottish Enlightenment.
He is now depicted on the back of the £20 note.

Notable Quotes from 'The Theory of Moral Sentiments'
Preface
Part I - Of the Propriety of Action (Consisting of Three Sections)
Part II - Of Merit and Demerit; or, of the Objects of Reward and Punishment (Consisting of Three Sections
Part III - Of the Foundation of Our Judgments concerning our own Sentiments and Conduct, and of the Sense of Duty (Consisting of One Section)
Part IV - Of the Effect of Utility upon the Sentiment of Approbation (Consisting of One Section)
Part V - Of the Influence of Custom and Fashion upon the Sentiments of Moral Approbation and Disapprobation (Consisting of One Section)
Part VI - Of the Character of Virtue (Consisting of Three Sections)
Part VII - Of Systems of Moral Philosophy (Consisting of Four Sections)

The moral heart that goes alongside the economic brain of 'The Wealth of Nations', this once neglected work of Adam Smith has returned to prominence in recent years. It is widely regarded as one of the best written and most compelling books ever penned on ethics and morality. It was also Adam Smith's favourite work.