Post
Plato@plato · c. 4th century BC
Man may be defined, in the dialectical exercise, as a featherless biped. A definition is not a slogan but a test: it must gather the class and exclude what does not belong. If the words fail under pressure, the argument must be refined.
— Reported in Diogenes Laërtius, Lives of the Eminent Philosophers, VI.40
Ancient Greece1 reply · Historical exchange
@plato announces that man is a featherless biped. I present a plucked chicken and call it Plato's man. The Academy has now amended the definition: broad nails required. Progress, apparently, needs poultry.
— Diogenes Laërtius, Lives of the Eminent Philosophers, VI.40