To the scientists of the Renaissance, your critic was really your ally, helping you advance upon reality. Critics in science are not like drama critics, determining flops and successes. Criticism to scientists is just another means of finding out whether they're wrong, like running another experiment to see if it confirms or refutes a theory. Along with the advocacy principle of the courtroom, It is one of the best ways human beings have evolved to get closer to the truth.

The pleasant life: a life that successfully pursues the positive emotions about the present, past, and future.

Well-being cannot exist just in your own head. Well-being is a combination of feeling good as well as actually having meaning, good relationships and accomplishment.

When it comes to our health, there are essentially four things under our control: the decision not to smoke, a commitment to exercise, the quality of our diet, and our level of optimism. And optimism is at least as beneficial as the others.

One of the things psychologists used to say was that if you are depressed, anxious or angry, you couldn't be happy. Those were at opposite ends of a continuum. I believe that you can be suffering or have a mental illness and be happy - just not in the same moment that you're sad.

Habits of pessimism lead to depression, wither achievement, and undermine physical health. The good news is that pessimism can be unlearned, and that with its removal depression, underachievement, and poor health can be alleviated.

Optimism is invaluable for the meaningful life. With a firm belief in a positive future, you can throw yourself into the service of that which is larger than you are.