Shakespeare - Sonnets 118

Like as to make our appetite 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 t' 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 feil sick of you.

William Shakespeare