From this background in the physical sciences, Cattell developed the belief that all fields are best understood by first seeking to find the fundamental underlying elements in that domain, and then developing a valid way to measure and research these elements (Cattell, 1965). Personality research author Schuerger stated that: When Cattell moved from the physical sciences into the field of psychology in the 1920s, he described his disappointment about finding that it consisted largely of a wide array of abstract, unrelated theories and concepts that had little or no scientific bases. He found that most personality theories were based on philosophy and on personal conjecture, or were developed by medical professionals, such as Jean Charcot and Sigmund Freud, who relied on their personal intuition to reconstruct what they felt was going on inside people, based on observing individuals with serious psycho-pathological problems. Cattell (1957) described the concerns he felt as a scientist:  Thus, Cattell's goal in creating the "16PF Questionnaire" was to discover the number and nature of the fundamental traits of human personality and to develop a way to measure these dimensions. At the University of London, Cattell worked with Charles Spearman who was developing factor analysis to aid in his quest to discover the basic factors of human ability. Cattell thought that could also be applied to the area of personality. He reasoned that human personality must have basic, underlying, universal dimensions just as the physical world had basic building blocks (like oxygen and hydrogen). He felt that if the basic building blocks of personality were discovered and measured, then human behavior (e.g., creativity, leadership, altruism, or aggression) could become increasingly understandable and predictable. In 1936 Gordon Allport and H.S. Odbert hypothesized that:  This statement has become known as the Lexical Hypothesis, which posits that if there is a word for a trait, it must be a real trait. Allport and Odbert utilized this hypothesis to identify personality traits by working through two of the most comprehensive dictionaries of the English language available at the time, and extracting 18,000 personality-describing words. From this gigantic list they extracted 4500 personality-describing adjectives which they considered to describe observable and relatively permanent traits. Cattell and his colleagues began a comprehensive program of international research aimed at identifying and mapping out the basic underlying dimensions of personality. Their goal was to systematically measure the widest possible range of personality concepts, in a belief that "all aspects of human personality which are or have been of importance, interest, or utility have already become recorded in the substance of language" (Cattell, R. B., 1943, p. 483).