From Milton Glaser’s “Ten Things I Have Learned” (Milton Glaser: 22 November 2001):
… the important thing that I can tell you is that there is a test to determine whether someone is toxic or nourishing in your relationship with them. Here is the test: You have spent some time with this person, either you have a drink or go for dinner or you go to a ball game. It doesn’t matter very much but at the end of that time you observe whether you are more energised or less energised. Whether you are tired or whether you are exhilarated. If you are more tired then you have been poisoned. If you have more energy you have been nourished. The test is almost infallible and I suggest that you use it for the rest of your life.