We'll take the view that nothing can have meaning by itself, but only in relation to whatever other meanings we already know. One might complain that this has the quality of the old question, Which came first, the chicken or the egg? If each thing one knows depends on other things one knows, isn't that like castles built on air? What keeps them from all falling down, if none are tied to solid ground?
Well, first, there's nothing basically wrong with the idea of a society in which each part lends meaning to the other parts. Some sets of thoughts are much like twisted ropes or woven cloths in which each strand holds others both together and apart. Consider all the music tunes you know. Among them you can surely find two tunes of which you like each one the more because of how it's similar to or different from the other one. Besides, no human mind remains entirely afloat. Later we'll see how our conceptions of space and time can be based entirely on networks of relationships, yet can still reflect the structure of reality.
If every mind builds somewhat different things inside itself, how can any mind communicate with a different mind? In the end, surely, communication is a matter of degree but it is not always lamentable when different minds don't understand each other perfectly. For then, provided some communication remains, we can share the richness of each other's thoughts. What good would other people be if we were all identical? In any case, the situation is the same inside your mind — since even you yourself can never know precisely what you mean! How useless any thought would be if, afterward, your mind returned to the selfsame state. But that never happens, because every time we think about a certain thing, our thoughts go off in different ways.
The secret of what anything means to us depends on how we've connected it to all the other things we know. That's why it's almost always wrong to seek the real meaning of anything. A thing with just one meaning has scarcely any meaning at all.
An idea with a single sense can lead you along only one track. Then, if anything goes wrong, it just gets stuck — a thought that sits there in your mind with nowhere to go. That's why, when someone learns something by rote — that is, with no sensible connections — we say that they don't really understand. Rich meaning-networks, however, give you many different ways to go: if you can't solve a problem one way, you can try another. True, too many indiscriminate connections will turn a mind to mush. But well-connected meaning-structures let you turn ideas around in your mind, to consider alternatives and envision things from many perspectives until you find one that works. And that's what we mean by thinking!