It is usual to classify the criminal according to the crimes he commits. One classification, for example, makes murderers the least intelligent; vagabonds, sexual offenders, and highwaymen a little more so; while the fraudulent class, pickpockets and burglars, are accounted the most gifted of all. I think this a fair division and one that will generally hold good; but I have found that criminals who commit crimes against property, or the fraudulent class, are far and away in the majority. Their native intelligence will compare favorably with that of the average run of people; and I have been unable to discover any mental defects until they have been a long time in prison. Nearly all of them can read and write very well indeed; and there are many who have read far more than the ordinary business man. I have met men, very low-born men too, who, while in prison, have read through more volumes of philosophy and history than even the usual college student can boast in his reading; and they have been able to converse very wisely on these subjects. These same men have acquired the rudiments of their studies in reformatory and industrial institutions, and have succeeded in continuing them in the libraries of penitentiaries. I know one criminal who in his prison-cell informed himself about a branch of chemistry simply for purposes of business: he was thought at the time to be more or less crazy. Prison officials are often deceived by criminals in regard to their acquirements in learning. In many prisons, diligence and progress in study earn as much promotion as general good conduct does; and as the average prisoner has every reason to desire the benefits which promotions bring with them, he tries after a fashion to progress. But what is this fashion? Very frequently this: On his arrival at the prison, instead of telling the truth to the officials who quiz him about his abilities, he says that he does not even know the alphabet, and is consequently given very light mental work. He is thus able to advance rapidly, and his teachers pride themselves on his quickness to learn and their ability to teach. Ere long he gets into a better class, and so on until he has enjoyed all the benefits which precocity can earn. There are other men who profess ignorance in order to appear simple and unknowing, and thus create the impression that they are not so guilty as they are taken to be. Many times and in many cases the criminal is a little cleverer than the people who are examining him; and one cannot set a high value on statistics concerning his intelligence. If the student of criminology could and would eavesdrop for a while at some "hang-out" in the open, and hear the criminal's own account of the way he is investigated, he might learn "foxier" methods of dealing with his subject.