Ética, Parte III, Definición de los afectos 15

Thus confidence springs from hope, and despair from fear, when all cause for doubt as to the issue of an event has been removed: this comes to pass, because man conceives something past or future as present and regards it as such, or else because he conceives other things, which exclude the existence of the causes of his doubt. For, although we can never be absolutely certain of the issue of any particular event (II. xxxi. Coroll.), it may nevertheless happen that we feel no doubt concerning it. For we have shown, that to feel no doubt concerning a thing is not the same as to be quite certain of it (II. xlix. note). Thus it may happen that we are affected by the same emotion of pleasure or pain concerning a thing past or future, as concerning the conception of a thing present; this I have already shown in III. xviii., to which, with its note, I refer the reader.