"Believe nothing you hear, and only one half that you see."
This wise little maxim is taken from The System Of Dr Tarr And Prof Fether, a short story by the American writer Edgar Allan Poe.
It is one of those sayings that gets bandied about sometimes on Facebook, and is often attributed to Benjamin Franklin - one of the United States' founding fathers.
As far as I can ascertain, Franklin never actually said it - which just goes to show that you really can only believe half of what you see.
You see a lot of fake quotes on the Internet. For example, just this week I have seen quotations falsely attributed to Einstein, Buddha and the Dalai Lama.
The Einstein one goes like this: "Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid."
My wife, Wendy, and I have different opinions about this.
She thinks that if the sentiment expressed is a nice one, it matters little whether Einstein, Buddha or the Dalai Lama really said it or not.
I am of the opinion that it does matter, and that it is wrong to put people's names to ideas and sentiments that they have never expressed.
But I digress.
My real point is that we cannot assume something is true just because we have heard it from someone, or read it somewhere.
And yet we often do.
For example, if a friend tells us a story about some kind of conflict she had with, say, her partner, our natural reaction is to take her version of events largely on trust.
We cannot help but feel irritated by her partner's behaviour.
But if we had heard the same story from her partner, the same events would have been portrayed very differently - and perhaps no less truthfully.
In his classic 18th-century novel, Tom Jones, the English playwright and novelist Henry Fielding remarks: "Let a man be never so honest, the account of his own conduct will, in spite of himself,
be so very favourable, that his vices will come purified through his lips, and, like foul liquors well strained, will leave all their foulness behind."
It is human nature.
We, all of us, find it impossible to speak or write about ourselves and our conduct without taking a few liberties with the circumstances, motives and consequences.
That is why I smiled wryly when I recently came across a book review that described a celebrity's new autobiography as "honest".
It is not the first time I have seen an autobiography described in such a fashion.
What I would like to know is: Who says the writer is honest?
As far as I can tell, books get labelled "honest" if the writer admits to having made some mistakes or committed some misdeeds. But this misses what I think is a very obvious point.
Namely, that the writer gets to choose which mistakes and misdeeds to relate and gets to decide how to portray them.
How many of us, if we were to write the story of our lives, would have the courage - or even the self-awareness - to reveal the naked truth about ourselves?
The French writer, Francois de La Rochefoucauld once said: "We confess our little faults to persuade people that we have no large ones."
We do, indeed.
So, confessing to mistakes and misdeeds is by no means an indication of honesty and transparency.
As the German philosopher Friedrich Nietzsche once observed: "Talking much about oneself can also be a means to conceal oneself."