Nothing in life is certain except death, taxes and the second law of thermodynamics.

Faith means living with uncertainty - feeling your way through life, letting your heart guide you like a lantern in the dark.

Probability is expectation founded upon partial knowledge. A perfect acquaintance with all the circumstances affecting the occurrence of an event would change expectation into certainty, and leave nether room nor demand for a theory of probabilities.

There are things known and there are things unknown, and in between are the doors of perception.

We know from chaos theory that even if you had a perfect model of the world, you'd need infinite precision in order to predict future events. With sociopolitical or economic phenomena, we don't have anything like that.

There are things known and there are things unknown, and in between are the doors of perception.

If we must not act save on a certainty, we ought not to act on religion, for it is not certain. But how many things we do on an uncertainty, sea voyages, battles!

Without the element of uncertainty, the bringing off of even, the greatest business triumph would be dull, routine, and eminently unsatisfying.

Faith and doubt both are needed - not as antagonists, but working side by side to take us around the unknown curve.

Human spirit is the ability to face the uncertainty of the future with curiosity and optimism. It is the belief that problems can be solved, differences resolved. It is a type of confidence. And it is fragile. It can be blackened by fear and superstition.

Uncertainty is a permanent part of the leadership landscape. It never goes away.

The uncertainty principle refers to the degree of indeterminateness in the possible present knowledge of the simultaneous values of various quantities with which the quantum theory deals; it does not restrict, for example, the exactness of a position measurement alone or a velocity measurement alone.

From an early age I was very, very fascinated by uncertainty.

I think we spend so much of our lives trying to pretend that we know what's going to happen next. In fact we don't. To recognize that we don't know even what will happen this afternoon and yet having the courage to move forward - that's one meaning of faith.

Creativity requires the courage to let go of certainties.

One thing that being a scientist has taught me is that you can never be certain about anything. You never know the truth. You can only approach it and hope to get a bit nearer to it each time. You iterate towards the truth. You don't know it.

Dogmatism and skepticism are both, in a sense, absolute philosophies; one is certain of knowing, the other of not knowing. What philosophy should dissipate is certainty, whether of knowledge or ignorance.

In law, nothing is certain but the expense.

We have to have a way of dealing with this that engenders confidence, trust, gives us every chance of getting the right outcome and boosts both sustainability and economic return at the same time.

Doubt grows with knowledge.

In the future, instead of striving to be right at a high cost, it will be more appropriate to be flexible and plural at a lower cost. If you cannot accurately predict the future then you must flexibly be prepared to deal with various possible futures.

Uncertainty is the refuge of hope.

The affairs of this world are so shifting and depend on so many accidents, that it is hard to form any judgment concerning the future; nay, we see from experience that the forecasts even of the wise almost always turn out false.

Fear comes from uncertainty. When we are absolutely certain, whether of our worth or worthlessness, we are almost impervious to fear.

Medicine is a science of uncertainty and an art of probability.

Nobody knows the future with certainty. We can, however, identify ongoing patterns of change.

The future is no more uncertain than the present.

From principles is derived probability, but truth or certainty is obtained only from facts.

The known is finite, the unknown infinite; intellectually we stand on an islet in the midst of an illimitable ocean of inexplicability. Our business in every generation is to reclaim a little more land, to add something to the extent and the solidity of our possessions.

We know accurately only when we know little, with knowledge doubt increases.

A man doesn't know what he knows until he knows what he doesn't know.

Birth and death; we all move between these two unknowns.

When we step into a new terrain, we experience vast uncertainty. Uncertainty is just a situation that you do not know how to handle.

The older I get, the less I know. By that I mean the less I am sure of. I view people with strong opinions on the big stuff with distrust. I don't think we should have certain certainties on faith and politics; I think we should be open-minded.

Some of our important choices have a time line. If we delay a decision, the opportunity is gone forever. Sometimes our doubts keep us from making a choice that involves change. Thus an opportunity may be missed.

Isn't it the moment of most profound doubt that gives birth to new certainties? Perhaps hopelessness is the very soil that nourishes human hope; perhaps one could never find sense in life without first experiencing its absurdity.

We often call a certainty a hope, to bring it luck.

Uncertainty is not an indication of poor leadership; it underscores the need for leadership.

Life is full of change and uncertainty. We know this. We experience it on a daily basis.

There's a constant tension between the excitement of new people and security with one person. If you go with excitement, you create chaos; you hurt people. There's jealousy, and it gets very messy. If you have security, it can be boring, and you die inside because of all the opportunities missed.

All imaginable futures are not equally possible.

There is an immutable conflict at work in life and in business, a constant battle between peace and chaos. Neither can be mastered, but both can be influenced. How you go about that is the key to success.

In this world nothing can be said to be certain, except death and taxes.

Action and reaction, ebb and flow, trial and error, change - this is the rhythm of living. Out of our over-confidence, fear; out of our fear, clearer vision, fresh hope. And out of hope, progress.

Basically, there are two paths you can walk: faith or fear. It's impossible to simultaneously trust God and not trust God.

I'm sad to report that in the past few years, ever since uncertainty became our insistent 21st century companion, leadership has taken a great leap backwards to the familiar territory of command and control.

Uncertainty always creates doubt, and doubt creates fear.

Investing is about predicting the future, and the future is inherently unpredictable. Therefore, the only way you can do better is to assess all the facts and truly know what you know and know what you don't know. That's your probability edge.

Sooner or later you must move down an unknown road that leads beyond the range of the imagination, and the only certainty is that the trip has to be made.

In times of uncertainty, employees crave clarity. As a leader, you won't always have all of the answers - no one expects you to - so you must be open to listening and learning from others. Once you understand a particular challenge and outline the options, you have to be confident in making bold and optimistic decisions.

The future continues to preoccupy me as a reliable source of hopes, fears and anxieties, but increasingly the present seems to have no outstanding qualities of its own, being merely a way-station through which events travel to the vast shadow lands of the past.

I have devoted my life to uncertainty. Certainty is the death of wisdom, thought, creativity.

Markets are constantly in a state of uncertainty and flux and money is made by discounting the obvious and betting on the unexpected.

Fear is often our immediate response to uncertainty. There's nothing wrong with experiencing fear. They key is not to get stuck in it.

Science means constantly walking a tightrope between blind faith and curiosity; between expertise and creativity; between bias and openness; between experience and epiphany; between ambition and passion; and between arrogance and conviction - in short, between an old today and a new tomorrow.