These fields seem to be of a remarkably narrow extent. Besides specialists (numismatists, zoologists, botanists, heralds, etc.) who, apart from their stupendous memory for their particular matters, appear to have no memory for other things, there are people who can remember only rhymes, melodies, shapes, forms, titles, modes, service, relationships, etc. V. Volkmar has devoted some space to showing this. He has also called attention to the fact that the semi-idiotic have an astounding memory for certain things. This has been confirmed by other students. One of them, Du Potet,[224] who is perhaps the expert in the popular mind of the Austrian Alps, has made it especially clear. As in all mountainous regions there are a great number of those unfortunate idiots who, when fully developed, are called cretins, and in their milder form are semi-human, but do not possess intelligence enough to earn their own living. Nevertheless, many of them possess astounding memories for certain things. One of them is thoroughly conversant with the weather prophecy in the calendar for the past and the present year, and can cite it for each day. Another knows the day and the history of every saint of the Catholic church. Another knows the boundaries of every estate, and the name, etc., of its owner. Another knows each particular animal in a collective herd of cattle, knows to whom it belongs, etc. Of course not one of these unfortunates can read. Drobisch mentions an idiotic boy, not altogether able to speak, who, through the untiring efforts of a lady, succeeded finally in learning to read. Then after hasty reading of any piece of printed matter, he could reproduce what he had read word for word, even when the book had been one in a foreign and unknown tongue. Another author mentions a cretin who could tell exactly the birthdays and death-days of the inhabitants of his town for a decade.