ABSTRACT
Galen did not speculate on the infant profiles of melancholic and sanguine adults, but he would have been pleased with the fact that a cautious or relaxed reaction to novelty is preserved from very early childhood to adolescence. Philosophers ask three fundamental questions about natural phenomena: What is it? How do we determine what it is? What are its functional consequences? Temperament is an inherited profile of behaviour, affect, and physiology that is best discovered by observing directly the young child's psychological and biological reactions to specific incentives and charting how these initial biases lead to distinctly different envelopes of behaviour and mood that are moderately stable over later childhood and adolescence. The most popular concepts in personality refer to qualities like sociable, agreeable, anxious, depressed, or conscientious. Understanding the origins of these qualities is frustrated by the mystery surrounding their developmental origins and physiological correlates.
