Brain Fog!

"There are, however, no sharp lines or demarcations between the various operations just outlined.[thought and belief] The problem of attaining correct habits of reflection would be much easier than it is, did not the the different modes of thinking blend insensibly into one another."

-John Dewey, How We Think

"We ought to consider no only that our life is daily wasting away and a smaller part of it is left, but another thing which must be taken into account, that if a man should live longer, it is quite uncertain whether the understanding will continue sufficient for the comprehension of things, and retain the power of contemplation which strives to acquire the knowledge of the divine and the human.

For if we being to fall into dotage, perspiration and nutrition and imagination and the appetite, and whatever else there is of the kind, will not fail; but the power of making use of ourselves, and filling up the measure of our duty, and clearly separating appearances, and considering whether a man should now depart from life, and whatever else kind absolutely requires a disciplined reason, all this is already extinguished.  We must make haste then, not only because we are daily nearer to death, but also because the conception of things and understanding of them cease first."

-Marcus Aurelius, Meditations, book three.

"So far there is the same sort of situation as when one looking at a cloud is reminded of a human figure and face.  Thinking in both of these cases(the cases of belief and of fancy) involves a noted or perceived fact, followed by something else which is not observed but which is brought to mind, suggested by the thing seen.  

One reminds us, as we say, of the other."

-John Dewey, How We Think.