I will here draw attention to the fact, in order to indicate where error lies, that the imaginations of the mind, looked at in themselves, do not contain error.

The mind does not err in the mere act of imagining, but only in so far as it is regarded as being without the idea, which excludes the existence of such things as it imagines to be present to it.

If the mind, while imagining non--existent things as present to it, is at the same time conscious that they do not really exist, this power of imagination must be set down to the efficacy of its nature, and not to a fault, especially if this faculty of imagination depend solely on its own nature--that is (I.Def.
vii.), if this faculty of imagination be free.
PROP.XVIII.

If the human body has once been affected by two or more bodies at the same time, when the mind afterwards imagines any of them, it will straightway remember the others also.
Proof .-- The mind (II.xvii.

Coroll.) imagines any given body, because the human body is affected and disposed by the impressions from an external body, in the same manner as it is affected when certain of its parts are acted on by the said external body; but (by our hypothesis) the body was then so disposed, that the mind imagined two bodies at once; therefore, it will also in the second case imagine two bodies at once, and the mind, when it imagines one, will straightway remember the other.