A few data may illustrate what we have just said. Until the last decades of the nineteenth century psychology has not been able to support a journal of its own. A few attempts in this direction were made in the eighteenth century, when two psychological periodicals were started; but neither published more than a few volumes. Even in the middle of the last century magazine articles of psychological content were rare enough and appeared only in philosophical, physiological, or physical journals. During the last thirty years a complete revolution has taken place in this respect, more remarkable than in any other branch of science. First at longer intervals, then in quick succession, numerous purely psychological journals were founded in the principal civilized countries, of which none thus far has been compelled to retire on account of lack of either contributors or readers. We count at present at least fifteen, six of them in German, four in English, three in French, one in the Italian language, and one representing the Scandinavian peoples. And there is an equal number of periodical publications of single investigators and institutions, and also numerous writings of psychological importance published in philosophical, physiological, psychiatrical, pedagogical, criminological, and other journals. QUESTIONS 1. How old is the science of psychology? 2. What do you know about its early growth? 3. What are the difficulties besetting psychology? 4. What is the origin of popular psychology? 5. Why is psychology so much hampered by prejudice? 6. State the two ways in which psychology has been influenced by natural science. 7. How was psychology influenced by medieval theology? 8. Who were the opponents of theological psychology? 9. What does freedom of action mean? 10. What kind of ignorance is the cause of the belief in absolute freedom? 11. How did the associational psychology originate? 12. What is meant by the faculty psychology? 13. What does psychology owe to Herbart? 14. What is voluntarism? 15. Why are mechanical explanations of mental life inadequate? 16. From which science can psychology obtain the most fruitful analogies? 17. Which science gave in the earlier part of the nineteenth century the strongest direct impulse to psychology? 18. What is psychophysics and who is its author? 19. What is meant by the personal equation? 20. What experimental investigations were suggested by the personal equation? 21. How did the study of the physiology of the brain influence psychology? 22. Is psychology a special science? CHAPTER I GENERAL PSYCHOLOGY § I. BRAIN AND MIND