In the West, we think of writing as capturing the sounds and content of spoken language. Ancient Chinese was something else entirely. It was designed not to capture spoken words, but concepts. It served the purposes of both poetry, mathematics, and history. This is one reason why all translations of The Art of War into English prose miss so much of its content.
When we say that ancient Chinese is a conceptual language, we mean not only that it doesn't represent the sounds of a spoken tongue, but that it doesn't even represent the parts of speech we use in a spoken language. This means that the characters of ancient Chinese cannot be properly understood as verbs, nouns, adjectives, adverbs, and so on, as can words in other written languages. Each character can be any of these parts of speech.
Chinese characters are divided into two general types of characters, pictographs, that is, pictures of things, and ideographs, representing abstract idea. However, over time, most of these forms were combined to create a combination of the two. Ancient Chinese consisted entirely of these forms. However, 90% of modern written Chinese characters are semantic-phonetic compounds. The semantic part or radical suggests the meaning of the character. The phonetic component gives a clue to the pronunciation of the character. For examples, see this page.
Most of the ancient characters are still recognized (at least in how they are written today in brush script, but they are not necessary used in the same way. Let us explain. Ancient Chinese characters represent general concepts. The same character is used for all parts of speech. So the character (bing) can be translated as a noun—"an army," "a soldier," "war," or "competition"—or an adjective—"military," "martial," "competitive"—or as a verb—"to make war," "to soldier," "to compete," and so on. This gives the translator a wide choice of possible meanings. Today, different modern Chinese characters carry these various specific meanings so the character bing is not used nearly so broadly.
Because writing ideograms with a metal stylus on bamboo was time-consuming, many shades of meaning were condensed into a single character. In this regard, ancient Chinese is regarded as poetic because, as in modern poetry, a single idea or word symbolized or encapsulated many related ideas. A character took its specific meaning from its primitive parts, from its use with other characters, from its use earlier in the work, from its use in other works, and from the larger context of Chinese culture.
With such a broad array of possible interpretations, much of the intended meaning of a phrase comes from its larger context. Within the work, phrases, blocks, and chapters were carefully arranged. This organization provided additional context and meaning, especially when the writer used strict patterns in arranging his material as Sun Tzu did. Thus, each phrase of ancient Chinese becomes more like a single line in a mathematical proof. Taking it out of context can destroy its meaning. For example, although I can generally translate the concepts in the phrase
Back walls do not oppose,
we need a larger context to get the point. This is the context of the work itself, the specific chapter, block, and verse. The most important context is that of classical Chinese science and its many conventions, which Sun Tzu relied upon heavily in creating his system.