We have been warned:
Yet mark’d I where the bolt of Cupid fell:
It fell upon a little western flower,
Before, milk-white, now purple with love’s wound,
And maidens call it love-in-idleness.
Fetch me that flow’r; the herb I show’d thee once.
The juice of it, on sleeping eye lids laid,
Will make or man or woman madly dote
Upon the next live creature that it sees.
William Shakespeare “A Midsummer Night’s Dream” (Act 2, Scene 1)