To the community the criminal is aggressive. To the criminal his life is one of defense primarily. The greater part of his energy, of his hopes, and of his successes, centres around escapes, around successful flight, around proper covering-up of his tracks, and around having good, loyal, and trustworthy friends to participate in his activities, who will tell no tales and keep the rest of the community outside. The criminal is thus, from his own point of view--and I am speaking of professional criminals--living a life of defensive warfare with the community; and the odds are heavy against him. He therefore builds up a defensive psychology against it--a psychology of boldness, bravado, and self-justification. The good criminal--which means the successful one, he who has most successfully carried through a series of depradations against the enemy, the common enemy, the public--is a hero. He is recognized as such, toasted and feasted, trusted and obeyed. But always by a little group. They live in a world of their own, a life of their own, with ideals, habits, outlook, beliefs, and associations which are peculiarly fitted to maintain the morale of the group. Loyalty, fearlessness, generosity, willingness to sacrifice one's self, perseverance in the face of prosecution, hatred of the common enemy--these are the elements that maintain the morale, but all of them are pointed against the community as a whole.[48] The manner in which the principle of the primary group was applied at Sing Sing in dealing with the criminal within the prison walls is a still more interesting illustration of the fact that social problems are group problems.[49] Assuming, then, that every social group may be presumed to have its own (a) administrative, (b) legislative, and (c) human-nature problems, these problems may be still further classified with reference to the type of social group. Most social groups fall naturally into one or the other of the following classes: a) The family. b) Language (racial) groups. c) Local and territorial communities: (i) neighborhoods, (ii) rural communities, (iii) urban communities. d) Conflict groups: (i) nationalities, (ii) parties, (iii) sects, (iv) labor organizations, (v) gangs, etc. e) Accommodation groups: (i) classes, (ii) castes, (iii) vocational, (iv) denominational groups.