Phaedrus, Fables 4.3
fame coacta vulpes alta in vinea
uvam adpetebat, summis saliens viribus.
quam tangere ut non potuit, discedens ait:
‘nondum matura es; nolo acerbam sumere.’
qui facere quae non possunt, verbis elevant,
adscribere hoc debebunt exemplum sibi.
A fox, driven on by hunger, made his attack on a bunch of grapes on a tall vine, jumping up with all his strength. When he wasn’t able to touch it, he walked away saying, ‘You’re not ripe yet; I don’t want to eat a sour bunch.’ Those people who use words to make light of what they’re incapable of doing will need to take this as their model.