Full Idea
For contingent, men do not mean that which hath no cause, but that which hath not for cause any thing that we perceive, as when a traveller meets a shower, they both had sufficient causes, but they didn't cause one another, so we say it was contingent.
Gist of Idea
'Contingent' means that the cause is unperceived, not that there is no cause
Source
Thomas Hobbes (Of Liberty and Necessity [1654], §95)
Book Reference
'British Moralists 1650-1800 Vol. 1', ed/tr. Raphael,D.D. [Hackett 1991], p.65
A Reaction
Contingent nowadays means 'might not have happened', or 'does not happen in all possible worlds'. Personally I share Hobbes' doubts about the concept of contingency, and this is quite a good account of the misunderstanding.