The Only Secure Knowledge Is That I

Common Sense Is The Most Fairly Distributed Thing In The World, For Each One Thinks He Is So Well-endowed With It That Even Those Who Are Hardest To Satisfy In All Other Matters Are Not In The Habit Of Desiring More Of It Than They Already Have.

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?

If You Would Be A Real Seeker After Truth, It Is Necessary That At Least Once In Your Life You Doubt, As Far As Possible, All Things.

When Writing About Transcendental Issues, Be Transcendentally Clear.

By 'god', I Understand, A Substance Which Is Infinite, Independent, Supremely Intelligent, Supremely Powerful, And Which Created Both Myself And Everything Else [...] That Exists. All These Attributes Are Such That, The More Carefully I Concentrate On Them, The Less Possible It Seems That They Could Have Originated From Me Alone. So, From What Has Been Said It Must Be Concluded That God Necessarily Exists.