As a field of study, the subject matter of ethics is the moral life. The moral life itself has been variously understood, although two approaches have most fundamentally defined ethics. One approach emphasizes human fulfillment and happiness and results in a teleological ethic focusing on ends. The other approach emphasizes moral duty and results in a deontological ethic focusing on moral obligations apart from ends. Since Aristotle, three questions have shaped the discipline of ethics: 1) What is the nature of what is good or right? 2) What is the nature of human understanding and action, or how do you come to know and do the good or right? 3) What are the criteria for judging actions? Christian ethics considers the moral life with primary reference to understanding God through Jesus Christ. Scripture is a primary source for this understanding.