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: