Sonet 118 (Shakespeare)
Like as, to make our appetites more keen,

With eager compounds we our palate urge;

As, to prevent our maladies unseen,

We sicken to shun sickness when we purge;

Even so, being full of your ne'er-cloying sweetness,

To bitter sauces did I frame my feeding;

And, sick of welfare, found a kind of meetness

To be diseased, ere that there was true needing.

Thus policy in love, to anticipate

The ills that were not, grew to faults assured,

And brought to medicine a healthful state

Which, rank of goodness, would by ill be cured;

  But thence I learn and find the lesson true,

  Drugs poison him that so fell sick of you