P7: An affect cannot be restrained or taken away except by an affect opposite to, and stronger than, the affect to be restrained.

Dem.: An affect, insofar as it is related to the Mind, is an idea by which the Mind affirms of its body a greater or lesser force of existing than before (by the general Definition of the Affects ).

Next, this affection of the Body (by P5) receives from its cause its force for persevering in its being, which therefore, can neither be restrained nor removed, except by a corporeal cause (by IIP6) which affects the Body with an affection opposite to it (by IIIP5), and stronger than it (by A1).6 And so (by IIP12), the Mind will be affected with the idea of an affection stronger than, and opposite to, the first affection, i.e. (by the general Definition of the Affects), the Mind will be affected with an affect stronger than, and opposite to, the first affect, which will exclude or take away the existence of the first affect.

Therefore, an affect can neither be taken away nor restrained except through an opposite and stronger affect, q.e.d.

Cor.: An affect, insofar as it is related to the Mind, can neither be restrained nor taken away except by the idea of an opposite affection of the Body stronger than the affection through which it is acted on. For an affect through which we are acted on can neither be restrained nor taken away except by an affect stronger than it and contrary to it (by P7), i.e. (by the general Definition of the Affects), except by an idea of an affection of the Body stronger than and contrary to the affection through which we are acted on.