This section is from the "The New Student's Reference Work Volume 5: How And Why Stories" by Elinor Atkinson.
We need salt in our bodies to keep us healthy. Our blood is just about as salty as sea-water. Isn't that curious when we think that animal life began on our earth in the sea? Now salt melts or dissolves easily in water, and in our blood, until they become brine. If we eat salty food the body soon gets too much salt in it. The only way to get rid of it is to dilute it with water. When the body needs water it very promptly calls for it. We say we feel thirsty.' Salt isn't the only thing that makes us thirsty. Sugar, and many strong, hot spices heat the blood and need to be diluted with water and washed out.