Classical grammar words in the Dao De Jing
焉 yān
In the Dao De Jing, 焉 (yān) always closes a clause with the sense “in it, there, to it”, used 9 times: it stands for 于此, “at this”.
At the end of a clause, 焉 is a preposition and a pronoun in one: it stands for 于此, “in it, at it, there”. 荆棘生焉 closes the line “Where troops have camped, thorns and brambles grow” (chapter 30): 焉 is the “there”, the place where the troops camped. Because it closes the clause, it also sounds like a final particle, and some grammars call it one.
Elsewhere in classical Chinese 焉 can be a question word, “how, where”; the Dao De Jing never uses it that way. Modern Chinese keeps it in set phrases such as 心不在焉, “the mind is not there” (absent-minded).
焉 as “in it, from it”
Pattern verb + 焉
At the end of a clause, 焉 means “in it, there, to it”, pointing back to a place or thing just named. 师之所处，荆棘生焉 (chapter 30): “Where troops have camped, thorns and brambles grow”, that is, grow there. In 万物归焉而不为主 (chapter 34), “the myriad things return to it”, it stands for the great Way. In 信不足焉，有不信焉 (chapters 17 and 23), “Where trust is insufficient, there is distrust”, it is often read as close to a pure final particle.
9 times in 7 lines.
行不言之教，万物作焉而不辞，
carries out unspoken guidance. The myriad things conform to the same law, without a word.
Chapter 2, line 7信不足焉，有不信焉。
Where trust is insufficient, there is distrust.
Chapter 17, line 5信不足焉，有不信焉。
Where trust is insufficient, there is distrust.
Chapter 23, line 14域中有四大，而王居其一焉。
Within our realm there are four greatnesses, and the king is one of them.
Chapter 25, line 10师之所处，荆棘生焉。
Where troops have camped, thorns and brambles grow.
Chapter 30, line 4万物归焉而不为主，
the myriad things return to it, yet it does not act as their master:
Chapter 34, line 6
Show 1 more lines
夫两不相伤，故德交归焉。
Since neither harms the other, their virtue flows back to the people.
Chapter 60, line 5
How to tell them apart
In this book 焉 has one use, so the question to ask is what it points back to: “in what? to what?” Look a few words back. In 万物归焉 (chapter 34) it is the great Way that things return to; in 故德交归焉 (chapter 60), “their virtue flows back to the people”, it is the people.
Do not confuse it with the question word 焉, “how, where”, which comes before the verb (焉知, “how would one know?”) and does not occur in the Dao De Jing. A 焉 at the end of a clause is always this one.