CHAPTER XXI. 

 THE SENSES. 



1. Common Sensation and Special Senses. Each of us 

 has a great many fee/ings, or sensations, of different kinds. 

 We may be hungry or thirsty or tired or suffer pain in 

 a variety of ways. Such sensations as these tell us 

 about our own bodies. Hunger warns us to eat, nausea 

 or "sickness" that the stomach is not in a condition to 

 digest, pain that some part is diseased or injured and 

 needs attention. All these kinds of feeling are named 

 common sensations. 



Other kinds of sensations enable us to learn about 

 things outside of our bodies, and to perceive and use ob- 

 jects in the world around us. These sensations are 

 known as the " special senses;" they include sight, hear- 

 ing, smell, taste, and touch, which are commonly spoken 

 of as " the five senses." To these we should add the 

 temperature-sense, which often enables us to learn that 

 ^something is hot or cold without touching it or seeing 

 it. These senses have been well called the " gateways of 

 knowledge," because without them the mind would have 

 to remain in complete ignorance of the world and uni- 

 verse in which we live. 



i. How do we learn the needs of our own bodies? Examples? What 

 are these feelings called? What is the use of the special senses? 

 Name the " five senses." What is the temperature sense ? Why are 

 the senses called the gateways of knowledge ? 



