If good, why do I yield to that suggestion
Whose horrid image doth unfix my hair
And make my seated heart knock at my ribs,
Against the use of nature? Present fears
Are less than horrible imaginings:
My thought, whose murder yet is but fantastical,
Shakes so my single state of man, that function
Is smother’d in surmise, and nothing is
But what is not.

William Shakespeare (1564 – 1616)