Pains and other such sensory processes may be long or short, continuous or intermittent; but in spite of Longfellow’s ‘long, long thoughts’, I do not think a thought (say, that the pack of cards is on the table, or that Geach’s arguments are fallacious) can significantly be called long or short; nor are we obliged to say that in that case every thought must be strictly instantaneous.
… [W]hat I am suggesting is that thoughts have not got all the kinds of time-relations that physical events, and I think also sensory processes, have. One may say that during half an hour by the clock such-and-such a series of thoughts occurred to a man; but I think it is impossible to find a stretch of physical events that would be just simultaneous, or even simultaneous to a good approximation, with one of the thoughts in the series. I think Norman Malcolm was right when he said at a meeting in Oxford that a mental image could be before one’s mind’s eye for just as long as a beetle took to crawl across a table; but I think it would be nonsense to say that I ‘was thinking’ a given thought for the period of the beetle’s crawl — the continous past of ‘think’ has no such use.
— Peter Geach, God and the Soul, 1969