Lastly, to the prognostics of time to come, which are naturally but conjectures upon the experience of time past, and supernaturally, divine revelation, the same authors of the religion of the Gentiles, partly upon pretended experience, partly upon pretended revelation, have added innumerable other superstitious ways of divination, and made men believe they should find their fortunes, sometimes in the ambiguous or senseless answers of the priests at Delphi, Delos, Ammon, and other famous oracles; which answers were made ambiguous by design, to own the event both ways; or absurd, by the intoxicating vapour of the place, which is very frequent in sulphurous caverns: sometimes in the leaves of the Sibyls, of whose prophecies, like those perhaps of Nostradamus (for the fragments now extant seem to be the invention of later times), there were some books in reputation in the time of the Roman republic: sometimes in the insignificant speeches of madmen, supposed to be possessed with a divine spirit, which possession they called enthusiasm; and these kinds of foretelling events were accounted theomancy, or prophecy: sometimes in the aspect of the stars at their nativity, which was called horoscopy, and esteemed a part of judiciary astrology: sometimes in their own hopes and fears, called thumomancy, or presage: sometimes in the prediction of witches that pretended conference with the dead, which is called necromancy, conjuring, and witchcraft, and is but juggling and confederate knavery: sometimes in the casual flight or feeding of birds, called augury: sometimes in the entrails of a sacrificed beast, which was haruspicy: sometimes in dreams: sometimes in croaking of ravens, or chattering of birds: sometimes in the lineaments of the face, which was called metoposcopy; or by palmistry in the lines of the hand, in casual words called omina: sometimes in monsters or unusual accidents; as eclipses, comets, rare meteors, earthquakes, inundations, uncouth births, and the like, which they called portenta, and ostenta, because they thought them to portend or foreshow some great calamity to come: sometimes in mere lottery, as cross and pile; counting holes in a sieve; dipping of verses in Homer and Virgil; and innumerable other such vain conceits. So easy are men to be drawn to believe anything from such men as have gotten credit with them; and can with gentleness, and dexterity, take hold of their fear and ignorance.
Thomas Hobbes, Leviathan
It's more complicated than that!