There is not much I am certain about, but one thing I am certain of is human fallibility (I know, I know, contradictions in the first sentence…).
Any one who claims to know the whole truth is deluded or a liar.
No matter how wise and how learned a teacher, they can only deliver an incomplete wisdom and an incomplete truth.
As Montaigne says, we start out in a state of blissful ignorance and we spend our lives moving towards a state of maximal knowledge, an ideal of perfect knowledge. But we all get lost somewhere in-between. Neither ignorant, nor knowing.
The highest wisdom is appreciating one’s own ignorance.
But then the question: since we are the beneficiaries of thousands of years of recorded history, and there very wise men and wise women in every generation, do we not accrete more and more wisdom from the wisdom of history? That is, are we not moving closer to a complete picture of the truth and wisdom available to us?
I would say yes and no.
Yes, in that certainly we have access to greater and greater pools of wisdom, and the sum of that wisdom, helps bring us closer to something approaching complete - but I think we will always be getting closer, always approaching final wisdom and never arriving.
It’s like the way that some quantities can never be fully expressed as a decimal. Like Pi for example. With each added decimal place, we form a more detailed and accurate picture, but we can continue computing Pi on and on for infinity, and will never arrive at a complete description.
It is like Xeno’s paradox: something that moves ever closer to its target but never seems to reach it, having to cover an infinity of points, to arrive at a finite destination.