Science Is Practical Philosophy.

Doubt Is The Origin Of Wisdom

How Can You Be Certain That Your Whole Life Is Not A Dream?

Every Man Is Indeed Bound To Do What He Can To Promote The Good Of Others, And A Man Who Is Of No Use To Anyone Is Strictly Worthless.

...it Is Certain That I Am Really Distinct From My Body, And Can Exist Without It.

When I Consider This Carefully, I Find Not A Single Property Which With Certainty Separates The Waking State From The Dream. How Can You Be Certain That Your Whole Life Is Not A Dream?