P9: An affect whose cause we imagine to be with us in the present is stronger than if we did not imagine it to be with us.

Dem.: An imagination is an idea by which the Mind considers a thing as present (see its definition in IIP17 S), which nevertheless indicates the constitution of the human Body more than the nature of the external thing (by IIP16 C2). An affect, therefore (by the general Definition of the Affects), is an imagination, insofar as {the affect} indicates the constitution of the body. But an imagination (by IIP17) is more intense so long as we imagine nothing that excludes the present existence of the external thing. Hence, an affect whose cause we imagine to be with us in the present is more intense, or stronger, than if we did not imagine it to be with us, q.e.d.

Schol.: I said above (in IIIP18) that when we imagine a future or past thing, we are affected with the same affect as if we were imagining something present; but I expressly warned then that this is true insofar as we attend to the thing’s image only. For it is of the same nature whether we have imagined the thing as present or not. But I did not deny that it is made weaker when we consider as present to us other things, which exclude the present existence of the future thing. I neglected to point this out then, because I had decided to treat the powers of the affects in this Part.

Cor.: Other things equal, the image of a future or past thing (i.e., of a thing we consider in relation to a future or past time, the present being excluded) is weaker than the image of a present thing; and consequently, an affect toward a future or past thing is milder, other things equal, than an affect toward a present thing.