was clear the
| last time he observed it;  but presently he notes, while
| occupied primarily with other things, that the air is cooler.
| It occurs to him that it is probably going to rain;  looking up,
| he sees a dark cloud between him and the sun, and he then quickens
| his steps.  What, if anything, in such a situation can be called
| thought?  Neither the act of walking nor the noting of the cold
| is a thought.  Walking is one direction of activity;  looking and
| noting are other modes of activity. 