“I was telling you that the language which we use in common conversation is not precise. It is often ambiguous.”
“What does that mean, sir?” said Rollo.
“Why, language is ambiguous when it has two meanings,” said his father. “For instance, the word burning is used in conversation to express two or three very different things. If you put your finger upon hot iron, you say you have burned it. Burn, in that case, is the name of a painful feeling. But if you say you burned a piece of paper, you mean that you put it into the fire, and allowed it to be consumed. In that case, burning, instead of being the name of a painful feeling, is the name of a peculiar process by which the paper is consumed and destroyed. Thus the word burn is used to denote two very different effects. In fact, it is used in other senses besides these.”
“What others, sir?” asked Rollo.
“Why, when we say that a little girl was out in the sun, and burned her face and neck, we do not mean that her face and neck were consumed, or that they felt a painful sensation,—but that the skin was reddened by the sun’s heat. So, when we say that the grass was all burned up in the drought, we mean that it was dried and withered. Thus burned and burning are used to denote a great variety of effects produced by heat, which effects are very different from each other in their nature. So that, you see, when we are going to speak philosophically of that peculiar process by which bodies are actually consumed by fire, it becomes necessary to have some term to denote that process alone, and not all the other kinds of burning. Now, the word the philosophers use for this purpose is combustion. The burning of a stick of wood upon the fire is combustion, but the burning of your finger against a hot iron is not combustion, and the burning of bricks in a brick kiln is not combustion.”
“Nor the burning of the grass in the drought,” said Rollo.
“No,” said his father. “Thus you see that combustion is a term of precise and definite meaning; it denotes a particular process, and that alone. But burning is a vague and ambiguous term; it has a great many meanings, or, rather, it stands for a great many different effects, very much unlike in their character. In fact, they seem to be alike in no respect, except that they are all produced by heat.”
“Yes, father,” said Rollo, “I understand.”
“Sometimes,” added his father, “the word used in common life doesn’t mean enough, instead of meaning too much. For example, there is the word freeze. What is the meaning of the word freeze?”
“Why, it means,” said Rollo,—“freeze?—it means—water turning into ice.”