It thus stands in marked contrast to memory, which is a passive attitude of mind, becoming active only when it gives rise to the expectation of a recurrence of the event.[138] And now let us pass to the question whether expectation ever takes the form of immediate knowledge.

It may, perhaps, be objected that the anticipation of something future cannot be knowledge at all in the sense in which the perception of something present or the recollection of something past is knowledge.

But this objection, when examined closely, appears to be frivolous.

Because the future fact has not yet come into the sphere of actual existence, it is none the less the object of a perfect assurance.[139] But, even if it is conceded that expectation is knowledge, the objection may still be urged that it cannot be immediate, since it is the very nature of expectation to ground itself on memory.

I have already hinted that this is not the case, and I shall now try to show that what is called expectation covers much that is indistinguishable from immediate intuitive certainty, and consequently offers room for an illusory form of error.
Let us set out with the simplest kind of expectation, the anticipation of something about to happen within the region of our personal experience, and similar to what has happened before.