6 ideas
People treat 'he has no memory' as meaning 'he has no sense,' yet memory and understanding are separate faculties. A weak memory often coincides with strong judgment, because the mind cannot lean on stored authorities and must reason things out for itself.
A deficient memory forces brevity, because long stories that depend on recalled detail fall apart. It lets old injuries fade instead of hardening into grudges, and it makes familiar books and places feel new again. A lapse that seems purely a weakness can instead shape a more concise, less resentful, and more renewing way of living.
The truth-teller only has to recall what happened, while the liar has to recall what he invented and whom he told it to. Fabrications multiply the things a person must track, so without an excellent memory the liar eventually contradicts himself and is exposed.
Montaigne describes men who reshape their accounts to suit the interests of each powerful person they serve. Because every version is fitted to a different audience, their stories inevitably collide, and they are caught out in front of the very patrons they meant to please. Adjusting the truth for each listener destroys your own credibility.
To say something untrue that you believe is true is error, not lying. To lie is to speak against your own conscience, knowingly asserting what you believe to be false. The vice lies in the intent to deceive, not in the falsehood of the statement.
Society holds together only through speech, so a person who lies betrays the one tool humans have for understanding each other. Truth has one face, but falsehood has endless forms and can never be pinned down. For this reason Montaigne calls lying an accursed vice that must be rooted out in children from their first lies, and he holds that even silence is more sociable than falsehood.