This was the state of mind in which I paid my first visit to Italy and Sicily. When I arrived I found nothing whatever to please me in the tastes of a society devoted to Italian and Syracusan cookery, where happiness was held to consist in filling oneself full twice a day, never sleeping alone at night, and indulging in the other pursuits that go with such a way of living. Brought up from boyhood in such an environment no man under heaven could become wise - he would need to be endowed with a temperment altogether miraculous - nor would he be any more likely to acquire self-control and the other qualities which go to make up goodness. Similarly no state, whatever its constitution, can enjoy peace and quietness if the citizens believe luxury to be the only proper object of expenditure and hold that men should be free from all other business to devote themselves entirely to feasting and drinking and the pursuit of love.
- Plato, the Seventh letter.
Reputedly Socrates' metaphorical name for a way of life in which no mindspace is allotted for possibly unanswerable philosophical quandaries - inasmuch as a pig presumably doesn't have the intellectual capabilities of postulating as to the nature of the universe, truth, God, knowledge and the soul, someone who has been equipped with the requisite intellect and refuses to exercise it may as well, like a pig, not possess the capability at all.
Aristotle, the pupil of Socrates' pupil (Plato), arrived at much the same conclusion in his Nichomachian Ethics, coming from the other direction and dismissing a life dedicated to pleasure (hedone, presumably the satisfaction of simple physical urges - a good meal, a good shit, a good rut) as slavish and only fit for animals, then going through and back into familiar territory as he proposes that the highest happiness (eudaimonia) is only attainable through the philosophical speculation, or theoria, which is closest to the activities of the Gods.
For centuries afterwards, Stoics pulled out the same swinish rhetoric on followers of Epicurus, and in the nineteenth century John Stuart Mill said in Utilitarianism that it was better to be Socrates dissatisfied than a pig satisfied (or rather, "It is better to be a human being dissatisfied than a pig satisfied; better to be Socrates dissatisfied than a fool satisfied."), perhaps contradicting Aristotle's earlier premise about philosophy leading to happiness but still strongly in support of the examined life of philosophy as an important thing if not necessarily a successful route to happiness.
When contacted for a comment, local pigs were only heard to say "Oink," but it looked like they were smiling.
(contrast, perhaps, with Montaigne's account of Pyrrho's pig.)