II
In so far as we imagine any object to be necessary do we affirm its existence, and, on the other hand, we deny its existence in so far as we imagine it to be not necessary and therefore the emotion towards an object which we imagine as necessary, other things being equal, is stronger than that towards an object that is possible, contingent, or not necessary.
In so far as we imagine an object as contingent, we are not affected by the image of any other object which posits the existence of the first, but, on the contrary (by hypothesis), we imagine some things which exclude its present existence. But in so far as we imagine any object in the future to be possible do we imagine some things which posit its existence, that is to say, things which foster hope or fear, and therefore the emotion towards an object which we know does not exist in the present, and which we imagine as possible, other things being equal, is stronger than the emotion towards a contingent object.
The emotion towards an object which we imagine to exist in the present is stronger than if we imagined it as future, and is much stronger if we imagine the future to be at a great distance from the present time. The emotion, therefore, towards an object which we imagine will not exist for a long time is so much feebler than if we imagined it as present, and nevertheless is stronger than if we imagined it as contingent; and therefore the emotion towards a contingent object is much feebler than if we imagined the object to be present to us.
In so far as we imagine an object as contingent, we are affected with no image of any other object which posits the existence of the first. On the contrary, we imagine (by hypothesis) certain things which exclude its present existence. But in so far as we imagine it in relationship to past time are we supposed to imagine something which brings it back to the memory or which excites its image and therefore so far causes us to contemplate it as present. Therefore, the emotion towards a contingent object which we know does not exist in the present, other things being equal, will be weaker than the emotion towards a past object.
In these propositions I consider that I have explained why men are more strongly influenced by an opinion than by true reason, and why the true knowledge of good and evil causes disturbance in the mind, and often gives way to every kind of lust, whence the saying of the poet, "Video meliora proboque, deteriora sequor." The same thought appears to have been in the mind of the Preacher when he said, "He that increaseth knowledge increaseth sorrow." I say these things not because I would be understood to conclude, therefore, that it is better to be ignorant than to be wise, or that the wise man in governing his passions is nothing better than the fool, but I say them because it is necessary for us to know both the strength and weakness of our nature, so that we may determine what reason can do and what it cannot do in governing our emotions.