Full Idea
No fact is so simple that it is not harder to believe than to doubt at the first presentation.
Gist of Idea
Even simple facts are hard to believe at first hearing
Source
Lucretius (On the Nature of the Universe [c.60 BCE], II.1022)
Book Reference
Lucretius: 'On the Nature of the Universe', ed/tr. Latham,Ronald [Penguin 1951], p.90
A Reaction
Hence induction is just 'drumming it in' until you come to believe it. There are good evolutionary reasons why we should be like this, because we would otherwise believe all sorts of silly half-perceptions in the gloaming.