3.141 A proposition is not a mixture of words. – (In the same way that a musical theme is not [just] a mixture of notes.)
A proposition is articulated.
Wittgenstein says (Letters to Ogden, p. 24) that the main point is that a proposition is a structure, not a mixture. Obviously the order is essential in each case. To be a proposition, to have a meaning or sense, words must be combined grammatically (at least approximately). This is the precise way in which words must be combined to have a meaning. That is to say: “The dog bit the man” means something different than “The man bit the dog.” The meaning depends on the way in which the words are combined, and which combination means what depends on grammar.