What does it take to be creative?

Here’s a riddle:

The king and the poison…

A ruthless, paranoid king was afraid that one of his aides was going to poison him so he needed to come up with a creative solution to ensure he could survive any poisoning.

Fortunately it was a well-known fact in the kingdom that the only way to survive drinking poison was to drink an even stronger poison.

So the king thought to himself:

“I just need to get my hands on the most powerful poison in the land. That way, I’ll be able to survive if someone tries to poison me.”

The king thought up a wicked plan to get his hands on the most powerful poison. He summoned two pharmacists known for their ability to concoct powerful potions, and told them, “Come to the palace on Sunday with the most powerful poison you can make. Each of you will drink the other’s poison and then your own.

Obviously, the one who has prepared the stronger poison will survive. The other, I promise a respectable burial…”

The king thought that in this way he’d be able to get his hands on the most powerful poison in the land.

The two pharmacists went home lamenting about their poor fortune. One pharmacist, who was old and poor, told his wife to prepare for his death as he told her the story about the relentless king.

“But can’t you concoct a stronger poison than the other pharmacist?” asked his wife.

“No,” he answered, “he is richer and more knowledgeable – there’s no doubt that he’ll be able to mix the stronger poison.”

Suddenly the pharmacist’s wife came up with an idea… “I know how you can survive,” she told him…

What was her idea?