[P50: Anything whatever can be the accidental cause of Hope or Fear.

Dem.: This Proposition is demonstrated in the same way as P15. Consult it together with P18 S2.

Schol.: Things which are accidental causes of Hope or Fear are called good or bad omens.

And insofar as these same omens are causes of Hope or Fear, they are causes of Joy or Sadness (by the definitions of hope and fear—see P18 S2); consequently (by P15 C), we love them or hate them, and strive (by P28) either to use them as means to the things we hope for, or to remove them as obstacles or causes of Fear.

Furthermore, as follows from P25, we are so constituted by nature that we easily believe the things we hope for, but believe only with difficulty those we fear, and that we regard them more or less highly than is just. This is the source of the Superstitions by which men are everywhere troubled.

For the rest, I do not think it worth the trouble to show here the vacillations of mind which stem from Hope and Fear—since it follows simply from the definition of these affects that there is no Hope without Fear, and no Fear without Hope (as we shall explain more fully in its place). Moreover, insofar as we hope for or fear something, we love it or hate it; so whatever we have said of Love and Hate, anyone can easily apply to Hope and Fear.