Questions: In the 19th century, an important individual in the origin of personality psychology was Spinoza. Shakespeare. Darwin. Descartes. Leibnitz.

The answer is Charles Darwin.

Explanation for each option:

1. Spinoza: Baruch Spinoza was a 17th-century philosopher known for his work in ethics and rationalism. While his ideas about human nature and emotions have influenced various fields, he is not directly associated with the origin of personality psychology in the 19th century.

2. Shakespeare: William Shakespeare was a playwright and poet from the late 16th and early 17th centuries. Although his works explore human nature and personality, he is not considered a foundational figure in the scientific study of personality psychology.

3. Darwin: Charles Darwin, a 19th-century naturalist, is a key figure in the development of personality psychology. His theory of evolution by natural selection, particularly the concept of individual differences and adaptation, laid the groundwork for understanding personality traits as evolutionary adaptations.

4. Descartes: René Descartes was a 17th-century philosopher known for his contributions to philosophy and mathematics. His ideas about dualism and the nature of the mind influenced later psychological thought, but he is not directly linked to the 19th-century origins of personality psychology.

5. Leibnitz: Gottfried Wilhelm Leibniz was a 17th-century philosopher and mathematician. While his work in metaphysics and logic has had a lasting impact, he is not directly associated with the development of personality psychology in the 19th century.