A crucial analysis and discussion of three principles that have been crucial to the development of "moral thinking" as we understand it today: Utilitarianism, Egoism and Intuitionism. Sidgwick's examination of ethical behavior, and more importantly, how humans develop these standards, still informs Libertarian politics today. Sidgwick is one of the most highly respected philosophers from the Victorian era; his intensive investigation of how humans should pursue individual happiness with respect to the common good has provoked discussion and debate since it was first published in 1874. Sidgwick continued to amend and revise his work until he died in 1900.