Men are disturbed not by the things which happen, but by the opinion about the things.

It’s what a man thinks is true which controls his actions, not what is really true.

Men are mistaken in thinking themselves free; their opinion is made up of consciousness of their own actions, and ignorance of the causes by which they are determined.

Men's views of things are the result of their understanding alone. Their conduct is regulated by their understanding, their temper, and their passions.

Any reality is an opinion-we make up our own reality

It is not difficult for a man to make a series of true statements, all unimpeachably correct, and yet to be hopelessly wrong. This is not just because there are nearly always many other facts, which he has not chosen to state, which would fill out and could utterly transform the description of reality he is trying to foist upon us. If our perceptions of reality depend on facts, they also depend on our values, for these determine not only how we see the facts but also which facts we shall see. To an embittered man, for example, nearly everything will taste bitter, but this is both because he infects each new experience with his own bitterness and also because he consistently reaches out, with uncannily sure instinct, for those types of experience which will give him fresh cause for embitterment.

there are very few who can think, but every man wants to have an opinion; and what remains but to take it ready-made from others, instead of forming opinions for himself?

A system of opinions which, being founded on a system of accepted values, determines the attitudes and behavior of men with respect to desired objectives of development of the society, social group or individual.

Everyone is entitled to his own opinion, but not his own facts.

Few men think, yet all will have opinions. Hence men’s opinions are superficial and confused.

Men have an extraordinarily erroneous opinion of their position in nature; and the error is ineradicable.

In human affairs, all that endures is what men think.

Everything we hear is an opinion, not a fact. Everything we see is a perspective, not the truth. — MARCUS AURELIUS, PHILOSOPHER AND EMPEROR OF ROME, SECOND CENTURY BCE

We are ready to die for an opinion but not for a fact: indeed, it is by our readiness to die that we try to prove the factualness of our opinion.