We must be willing to let go of the life we planned so as to have the life that is waiting for us.
We have to live today by what truth we can get today and be ready tomorrow to call it falsehood.
A triangle, if it could speak, would in like manner say that God is eminently triangular, and a circle that the divine nature is eminently circular; and thus would every one ascribe his own attributes to God.
At the heart of science is an essential tension between two seemingly contradictory attitudes - an openness to new ideas, no matter how bizarre or counterintuitive they may be, and the most ruthless skeptical scrutiny of all ideas, old and new. This is how deep truths are winnowed from deep nonsense.
Philosophy begins when one learns to doubt - particularly to doubt one's cherished beliefs, one's dogmas and one's axioms.
In all affairs it's a healthy thing now and then to hang a question mark on the things you have long taken for granted.