The observation holds equally with respect to future events. If a future event be either much wished or dreaded, the mind, to gratify its passion, never fails to augment the probability beyond truth. The credit which in all ages has been given to wonders and prodigies, even the most absurd and ridiculous, is a strange phenomenon. Nothing can be more evident than the following proposition, That the more singular any event is, the more evidence is required. A familiar event daily occurring, being in itself extremely probable, finds ready credit, and therefore is vouched by the slightest evidence. But a strange and rare event, contrary to the course of nature, ought not to be easily believed. It starts up without connection, and without cause, so far as we can discover; and to overcome the improbability of such an event, the very strongest evidence is required. It is certain, however, that wonders and prodigies are swallowed by the vulgar, upon evidence that would not be sufficient to ascertain the most familiar occurrence. It has been reckoned difficult to explain this irregular bias of the mind. We are now no longer at a loss about its cause. The proneness we have to gratify our passions, which displays itself upon so many occasions, produces this irrational belief. A story of ghosts or fairies, told with an air of gravity and truth, raiseth an emotion of wonder, and perhaps of dread. These emotions tending strongly to their own gratification, impose upon a weak mind, and impress upon it a thorough conviction contrary to all sense and reason. Opinion and belief are influenced by propensity as well as by passion; for the mind is disposed to gratify both. A natural propensity is all we have to convince us, that the operations of nature are uniform. Influenced by this propensity, we often rashly conceive, that good or bad weather will never have an end; and in natural philosophy, writers, influenced by the same propensity, stretch commonly their analogical reasonings beyond just bounds. Opinion and belief are influenced by affection as well as by propensity. The noted story of a fine lady and a curate viewing the moon through a telescope is a pleasant illustration. I perceive, says the lady, two shadows inclining to each other, they are certainly two happy lovers. Not at all, replies the curate, they are two steeples of a cathedral. APPENDIX to Part V. _Concerning the methods which nature hath afforded for computing time and space._ I introduce here the subject proposed, because it affords several curious examples of the power of passion to adjust objects to its gratification; a lesson that cannot be too much inculcated, as there is not perhaps another bias in human nature that hath an influence so universal, and that is so apt to make us wander from truth as well as from justice.