Listening to a series of excellent dharma talks from the San Francisco Zen Center, I first learned about the ancient poem “Trust in Mind”^[Full text of the poem, “Xinxinming”.] by the Third Ancestor of the Zen tradition, Jianzhi Sengcan (鑑智僧璨)

It captures beautifully, even in translation, the essence of Zen.

“The Perfect Way is only difficult for those who pick and choose;
Do not like, do not dislike; all will then be clear.
Make a hairbreadth difference, and Heaven and Earth are set apart;
If you want the truth to stand clear before you, never be for or against.”

First, I’ve only seen this syntax referred to as “TK constructions” in one place and it seems that it’s not really referred to that way elsewhere.

What’s so interesting about this construction?

It’s this: in English we can say “We were talking about what you wanted.” But in Russian, you can’t glue the phrases together that readily. “what” must be in the prepositional case (о том ) for the sake of the first clause, but it also has to function as a direct object of хотела . Since it can’t exist in two cases at one, we have to glue it together somehow. That’s what this construction does.

The way we do that is like this: Мы говорили о том, что ты хотела.

Many prepositions will require this type of construction. For example:

Наше решение зависит от того, что он хочет. (“Our decision depends on what he wants.”)

These constructions can get quite complicated with two prepositions in two different clauses referring to the same thing appearing in two different cases. For example:

Мы думали о том, на чём вы вчера настаивали. (“We were thinking about what you were insisting on yesterday.”)