One thing I find is a constant experience in my life, as well as a major thread in human history, is that nearly everything I and we believe is untrue.
For example, I believe that I am sitting on a chair as I write this, a chair I have sat in many times before. But the truth is that I am not sitting on the chair, but levitating just ever so slightly above the chair, and I have never in my life made actual contact with the chair, or with any chair for that matter. The atoms making up my body and the atoms making up the chair wisely refuse to touch (as touching would make those atoms explode) and instead repel one another, holding me and the chair apart with an electromagnetic field of sub-microscopic proportions.
That much of what we think we know is incorrect is true no matter how intelligent or insightful we are into certain matters. Isaac Newton was as devoted to attempting to expand the knowledge of alchemy as he was in physics. But as laughable as his belief that there was a secret formula which would turn lead into gold was, his belief in Descartes’ concept of the Luminiferous ether was even more false, and far more influential. The belief that the universe was permeated by an invisible and weightless medium which permitted the movement of light waves through space lasted until Albert Michelson, the first American to win the Nobel Prize in Physics, disproved it by accident in 1887, exactly two hundred years after the publication of Newton’s Principia.