How man first learnt to invent words is unknown; in other words, the origin of language is a mystery. All we know is that man, (1) animals, somehow invented certain sounds to express thoughts, feelings, and (2) , so that they could communicate with each other; and that later they (3) certain signs, called letters, which could be written down. These sounds, whether spoken or written in letters, we call words. The (4) of words, then, lies in their associations—the things they bring up before our minds. Words become filled with meaning for us by (5) . The longer we live, the more certain words make us (6) the glad and sad events of our past. And the more we read and learn, the more the number of words that mean something to us increases.