I catch myself philosophizing most abstractly when first returning to consciousness in the night or morning. I make the truest observations and distinctions then, when the will is yet wholly asleep and the mind works like a machine without friction. I am conscious of having, in my sleep, transcended the limits of the individual, and made observations and carried on conversations which in my waking hours I can neither recall nor appreciate. As if in sleep our individual fell into the infinite mind, and at the moment of awakening we found ourselves on the confines of the latter. On awakening we resume our enterprise, take up our bodies and become limited mind again. We meet and converse with those bodies which we have previously animated. There is a moment in the dawn, when the darkness of the night is dissipated and before the exhalations of the day commence to rise, when we see things more truly than at any other time. The light is more trustworthy, since our senses are purer and the atmosphere is less gross. By afternoon all objects are seen in mirage.
Henry David Thoreau, Journals, 17th March 1852 *
The more narrowly we examine actual language, the sharper becomes the conflict between it and our requirement. (For the crystalline purity of logic was, of course, not a result of investigation: it was a requirement.) The conflict becomes intolerable; the requirement is now in danger of becoming empty.—We have got on to slippery ice where there is no friction and so in a certain sense the conditions are ideal, but also, just because of that, we are unable to walk. We want to walk: so we need friction. Back to the rough ground!
Wittgenstein, Philosophical Investications, s107