6.3611 We cannot compare any process with the “passage of time” – there is no such thing – but rather only with another process (perhaps with the working of the chronometer).
Hence the description of a temporal process is only possible if we rely on another process.
Exactly the same kind of thing goes for space. Where one, e.g., says that neither of two events (that are mutually exclusive) can occur, because no reason exists why the one rather than the other should occur, there it is really a matter of one not being at all able to describe one of the two events without some asymmetry existing. And if there is such an asymmetry, then we can understand this as the reason for the occurrence of the one and the non-occurrence of the other.
There is no such thing as the passage of time? Or there is no such thing as comparing a process with the passage of time? The latter sounds [even] more plausible. This all sounds like a kind of idealism. A pragmatic kind. Nordmann criticizes Wittgenstein for being “caught in the present” in the Tractatus on pp. 128-133. But, of course, it is at least possible that the idea that the world is all that is (present tense) the case is meant to be overcome and discarded. Indeed, Nordmann regards the book as being written in the subjunctive mood. It is, he thinks, a kind of reductio.