There's something I learned way back when in toxicology. "Poison is in the dosage".

Garrus said:

There's something I learned way back when in toxicology. "Poison is in the dosage".

The full quote is more or less: Everything is poison, and nothing is without poison. The dosage determines whether it kills or cures.

I may have garbled that somewhat, the original saying is in german, i think.