"The idea of the intangibility of a mental state ... is of the greatest importance? Why is it intangible? Isn't it because we refuse to count what is tangible about our state as part of the specific state which we are postulating?" (Wittgenstein)
Once you've given yourself the time and the space you need to write—once you've coordinated the here and now of your writing moment—writing is, in a certain sense, "easy". You have your entire vocabulary to draw on, and since you are, for the moment, alone and no one is watching, you can say whatever you want. The words won't even refuse to be combined in ungrammatical ways. Consider, by contrast, the mason or the carpenter, whose work is forever governed by the laws of physics. Sure, your pen or computer has to obey the laws of physics, but your words are free. It is no more difficult to write them down than to think them.
Perhaps this is why Roland Barthes thinks of writing as a sublime kind of freedom. And why Stephen King calls it, almost without metaphor or irony, a kind of telepathy. Because the materials of writing exert so little resistance against our choices, because words are almost made of nothing, are weightless and colourless (in the sense that their colour does not, normally, affect their meaning), we forget that they—the words—are what we are making our writing out of. Indeed, we forget that we are actually making something—sentences, paragraphs—not just doing something—writing. We think that writing is just the act of meaning, an entirely abstract activity. We think it is intangible.
Against this, let's remember James Randi's remark about Uri Geller. "If he's using his mind to bend those spoons," said Randi, "he's doing it the hard way." Geller also claimed to be telepathic. Now, in both cases, Geller was probably very intentionally concealing "what is tangible" about his act from the audience, namely, the important work that his hands were doing in bending the spoons. It was, in short, a trick. (I'm told he's now openly performing the trick as such; he has stopped calling himself a mystic.) To think of writing as some remarkable species of freedom, or a kind of telepathy, is, really, to think of it as a kind of magic. It is a refusal to count "what is tangible" about the activity as part of the specific activity we are doing. In reality, writing is just another thing we do with our hands. In really good writing, of course, like that of Barthes and King, that trick just happens to be concealed.