Lee Cronbach would later achieve immortality for his methodological contributions (e.g., coefficient α, construct validity, aptitude by treatment interactions, and generalizability theory). His first big splash, though, was a 1949 textbook Essentials of Psychological Testing. Last week I was reading the 1960 edition of his textbook and found this skillfully worded comparison:
“Factor analysis is in no sense comparable to the chemist’s search for elements. There is only one answer to the question: What elements make up table salt? In factor analysis there are many answers, all equally true but not equally satisfactory (Guttman, 1955). The factor analyst may be compared to the photographer trying to picture a building as revealingly as possible. Wherever he sets his camera, he will lose some information, but by a skillful choice he will be able to show a large number of important features of the building.” p. 259
Assessing Psyche, Engaging Gauss, Seeking Sophia 
Am saving Cronbach’s analogy for the next time someone tells me that he/she know what a factor means, especially when applied to an individual human being.