"There may be in the cup / A spider steep'd, and one
may drink; depart, / And yet partake no venom (for his knowledge / Is not
infected), but if one present / Th' abhorr'd ingredient to his eye, make
known / How he hath drunk, he cracks his gorge, his sides, / With violent
hefts. I have drunk, and seen the spider."
William Shakespeare: "The Winter's Tale", Act II,
Scene i.