Graphology to use it for personality evaluation, empirical studies fail to show the validity claimed by its supporters. The word "graphology" is derived from "grapho-" (from the Greek γραφή, "writing") and "logos" (from the Greek λόγος, which relates to discussion or theory). Jean-Charles Gille-Maisani stated in 1991 that Juan Huarte de San Juan's 1575 "Examen de ingenios para las ciencias" was the first book on handwriting analysis. In American graphology, Camillo Baldi's "Trattato come da una lettera missiva si conoscano la natura e qualita dello scrittore" from 1622 is considered to be the first book. Around 1830 Jean-Hippolyte Michon became interested
The Philadelphia study development to display any social significance. The nearly completed and most advanced changes displayed the most stability within the study and showed intermediate correlation with the middle classes. The new and vigorous changes—the focal point of the study—displayed the strongest curvilinearity and most clearly encompassed the linguistically innovative nature of the inner classes. Through these Results, Labov asserted the truth and significance of what he named the Curvilinear Principle. With the social information gathered from the interviews, he discovered that it is not the education or occupation factors that drove the middle class to spur linguistic change. Rather, it was