For example, examine the photograph of subject A in your training docket. Consider his morbidly misshapen features. Does he not resemble a criminal? Indeed he is a villain of the most depraved kind! So self-evident is his malevolence that a single glance, boosted by our natural intuition, is sufficient for us to indict him.
Of course, subject A is only a simple training example carefully selected to demonstrate the general principles of criminal physiognomy. In actual practice, criminal physiognomy employs a rigorous and scientific framework that must be strictly followed for full efficacy. If this framework is not adhered to, then one risks making the wrong arrests.
A mistake that is often made, sometimes even by experts, is to misattribute as a criminal a person who is merely ugly. The reason why this is wrong ought to be obvious. Remember this! A criminal is someone who has committed a crime! A person, however hideous, cannot be considered a criminal until he inevitably engages in his criminal activities. Regrettably, it is only after then that we can act to arrest the transgressor.