15. Do you know of people who have radically changed their views late in life? 16. Try to teach a dog or a cat a trick. What do you learn of importance about habit-formation? 17. What branches taught in school involve the formation of habits that are useful throughout life? 18. Make a list of the moral habits that should be formed in early years. 19. Write an essay on _Habit and Life_. 20. Make a complete outline of the chapter. REFERENCES FOR CLASS READING COLVIN AND BAGLEY: _Human Behavior_, Chapters XI and XVII. PILLSBURY: _Essentials of Psychology_, pp. 48-59; also Chapter XV. PYLE: _The Outlines of Educational Psychology_, Chapters X, XI, and XII. ROWE: _Habit Formation_, Chapters V-XIII. TITCHENER: _A Beginner's Psychology_, p. 169, par. 37. CHAPTER VII MEMORY =Perceptions and Ideas.= In a previous chapter, brief mention was made of the difference between perceptions and ideas. This distinction must now be enlarged upon and made clearer. Perceptions arise out of our sensory life. We see things when these things are before our eyes. We hear things when these things produce air vibrations which affect our ears. We smell things when tiny particles from them come into contact with a small patch of sensitive membrane in our noses. We taste substances when these substances are in our mouths. Now, this seeing, hearing, smelling, tasting, etc., is _perceiving_. We perceive a thing when the thing is actually at the time affecting some one or more of our sense organs. A perception, then, results from the stimulation of a sense organ. Perception is the process of perceiving, sensing, objects in the external world. Ideas are our _seeming_ to see, hear, smell, taste things when these things are not present to the senses. This morning I saw, had a _perception_ of, a robin. To-night in my study, I have an _idea_ of a robin. This morning the robin was present. Light reflected from it stimulated my eye. To-night, as I have an idea of the robin, it is not here; I only seem to see it. The scene which was mine this morning is now revived, reproduced. We may say, therefore, that ideas are the conscious representatives of objects which are not present to the senses. Ideas are revived experiences. Revived experience is memory. Since it is memory that enables us to live our lives over again, brings the past up to the present, it is one of the most wonderful aspects of our natures. The importance of memory is at once apparent if we try to imagine what life would be without it. If our life were only perceptual, if it were only the sights and sounds and smells and tastes of the passing moment, it would have little meaning, it would be bare and empty. But instead of our perceptions being our whole life, they are only the starting points of life. Perceptions serve to arouse groups of memory images or ideas, and the groups of ideas enrich the passing moment and give meaning to the passing perceptions, which otherwise would have no meaning.