Spinoza (trns Elwes):

Men would never be superstitious if they could govern all their circumstances by set rules, or if they were always favoured by fortune: but being frequently driven into straits where rules are useless, and being kept fluctuating pitiably between hope and fear by the uncertainty of fortune’s greedily coveted favours, they are consequently, for the most part, very prone to credulity. The human mind is readily swayed this way or that in times of doubt, especially when hope and fear are struggling for the mastery, though usually it is boastful, overconfident, and vain.