LaHaye's framework is built on a theory of temperament that traces its origins to ancient Greek medicine and was developed and refined through centuries of observation about how people differ fundamentally in their characteristic patterns of behaviour, emotion, and motivation. He identifies four primary temperaments. Sanguine: warm, enthusiastic, and talkative. Sanguines are naturally outgoing and find social interaction energising. They tend to be optimistic, expressive, and entertaining. Their weaknesses include difficulty with follow-through, shallow commitments, and a tendency to prioritise fun and social connection over discipline and difficult tasks. Choleric: strong-willed, decisive, and driven. Cholerics are natural leaders who are energised by challenges and results. They are confident, direct, and not easily discouraged. Their weaknesses include impatience with others, a tendency to run over people's feelings, and difficulty admitting they are wrong. Melancholy: thoughtful, analytical, and sensitive. Melancholics are gifted with deep thinking, high standards, and a strong aesthetic sense. They are often the most talented and creative of the temperaments. Their weaknesses include perfectionism that can become paralysing, a tendency toward self-criticism, and difficulty with relationships. Phlegmatic: calm, reliable, and diplomatic. Phlegmatics are the steadiest of the temperaments: unruffled by pressure, consistent, and easy to be around. Their weaknesses include passive resistance to change, a tendency to take the path of least resistance, and difficulty initiating or asserting themselves even when they should.