What exactly does 意 mean? If I'm not mistaken, this 300 BC Chinese philosophy is strikingly modern.

世之所贵道者，书也。书不过语，语有贵也。语之所贵者，意也，意有所随。意之所随者，不可以言传也，而世因贵言传书。Source: 轮扁斫轮 http://baike.baidu.com/view/238082.htm

For example, until one sees the colour red, he will never know what the colour red is. No verbal explanation can take the place of a demonstration.

In another example, no one can learn how to swim by just reading a book.

I wonder what exactly 意 means.
Modern translation of colloquial saying considered to be 意义 here, which in english is meaning, sense, ignificance, importance, bearing or something else.
But ancient words are very abstract, abbreviated, modern meanings can't mean the meaning itself.