All these conceptions are regarded as due to a fixed conventional idea that there was a 'normal' man, who led a good life, and an 'abnormal' man who led a bad life, and this misconception is held to have stood in the way of a scientific view of the nature of criminal man. "Scientifically," according to Dr. Goring, "we can only divide men into 'normal' and 'abnormal' when there is some qualitative difference. 'Normal' is the outcome of the natural laws of existence. This becomes 'abnormal' only when supplanted by some pathological process. Normal never 'merges' into the abnormal, _e.g._, the natural ranges of vesicular breathing, of normal temperature, of folly, and want of control, never merge into the morbid ranges of pneumonic breathing, fevers and madness. The qualities that have to be considered in relation to crime are not 'abnormal' qualities, but qualities common to all humanity. Law-breakers are not a special breed of human beings differing _qualitatively_ from those who keep the law: any difference there may be between these two human classes is of degree only and not of kind: and, similarly, law-breaking is not different in quality from all other forms of anti-social conduct for which men are not punished, even if they are found out: yet here again there is a vast range of difference in _degree_. And that is why statistical methods are necessary for the scientific study of the criminal. For only by measurement can difference of degree be evaluated; and statistics is merely a refined instrument for making measurements." The word 'criminal,' strictly-speaking, only designates the fact that an individual has been imprisoned: that he has committed a crime. The object of this inquiry is to determine whether certain constitutional, as well as environmental, factors play a part in the production of the criminal act. It is impossible to state dogmatically _à priori_ what these factors are, or which of them prevail in the determination of a given act, but it is lawful to assume from the phenomenon of crime that there is a hypothetical character of some kind, a constitutional proclivity, either mental, moral or physical, present, to a certain degree, in all individuals, but so potent in some as to determine for them the fate of imprisonment.