I am confused by the phrases like "то, что он пишет" and by the construction "то, что" in general. For example, let us consider this sentence:
(1) То, что он пишет, и так ясно.
However simple and natural this sentence may be for you, it is truly mind-blowing for such a poor student as I am. The Russian words "тo" and "что" are tricky words used as references, and it is especially confusing when they come together to form a complicated Russian logical structure.
I am so much puzzled as to which of the following three interpretations of Sentence (1) is correct:
(2) It is obvious anyway what is contained in his writings.
(3) It is obvious anyway that he is writing.
(4) The ideas he expresses in his writings are obvious anyway.
My question is this: What is the meaning of Sentence (1), and how does "то, что" work in general?
UPDATE: Reading answers and comments, I realized I have to explain the difference between Sentences (2) and (4).
Let's suppose that you are in the 1920s and that your friend tells you, "We know that Hitler writes a book in the prison, but I just learned more details: he writes that the Jews are an evil nation and that the Germans need more living space."
You respond, "I talked with Hitler a lot in the past, so even if you had not told me, I could make a pretty good guess what ideas he is putting on paper. It is obvious that he writes that the Jews are an evil nation and that the Germans need more living space." This is the same as Sentence (2).
Now imagine that you respond differently, "He writes very obvious things. It is so obvious anyway that the Jews are an evil nation and that the Germans need more living space." This is the same as Sentence (4).
Let me try to explain the same thing in Russian.
X says, "Гитлер пишет, что немцам нужно больше пространства."
Y says: "To, что он пишет, и так ясно."
Interpretation (2) of what Y said: И так ясно, что он пишет, что немцам нужно больше пространства.
Interpretation (4) of what Y said: И так ясно, что немцам нужно больше пространства.
I humbly hope that you now understand the difference.