Liberal education is liberation from vulgarity. The Greeks had a beautiful word for “vulgarity”; they called it apeirokalia, lack of experience in things beautiful. Liberal education supplies us with experience in things beautiful.
☛ “What Is Liberal Education?” by Leo Strauss, Liberalism Ancient and Modern, Chicago: University of Chicago Press,  1968, p. 8.
The text “What Is Liberal Education?” was originally presented as an address given at the Tenth Annual Graduation Exercises of the Basic Program of Liberal Education for Adults on June 6, 1959. The full text of Strauss’s address is available online.
The word is used both in Plato’s Republic and in Aristotle’s Nicomachean Ethics. In the translation he made of the former, Paul Shorey once translated ἀπειροκαλία by “want of taste” (Book III, 403c) and once by “shameful” (Book III, 405b) while adding this note:
There is no exact English equivalent for ἀπειροκαλία, the insensitiveness to the καλόν of the banausic, the nouveau riche and the Philistine. (Plato in Twelve Volumes, Vols. 5 & 6 translated by Paul Shorey. Cambridge, MA, Harvard University Press; London, William Heinemann Ltd. 1969; see Perseus)
Below are excerpts from both occurrence of the word, in Paul Shorey’s translation. First from Book III, 403c:
“Thus, then, as it seems, you will lay down the law in the city that we are founding, that the lover may kiss and pass the time with and touch the beloved as a father would a son, for honorable ends, if he persuade him. But otherwise he must so associate with the objects of his care that there should never be any suspicion of anything further, [403c] on penalty of being stigmatized for want of taste [ἀπειροκαλία] and true musical culture.”
Second also from Book III, 405b:
“Will you be able to find a surer proof of an evil and shameful state of education in a city than the necessity of first-rate physicians and judges, not only for the base and mechanical, but for those who claim to have been bred in the fashion of free men? Do you not think [405b] it disgraceful and a notable mark of bad breeding to have to make use of a justice imported from others, who thus become your masters and judges, from lack of such qualities in yourself?”
“The most shameful thing in the world.”
“Is it?” said I, “or is this still more shameful [ἀπειροκαλία]—when a man only wears out the better part of his days in the courts of law as defendant or accuser, but from the lack of all true sense of values is led to plume himself on this very thing, as being a smart fellow to ‘put over’ an unjust act [405c] and cunningly to try every dodge and practice, every evasion, and wriggle out of every hold in defeating justice, and that too for trifles and worthless things, because he does not know how much nobler and better it is to arrange his life so as to have no need of a nodding juryman?”
“That is,” said he, “still more shameful than the other.”
In Aristotle’s Nicomachean Ethics the word is used in Book II, chapter 7, section 6 (1107b). It is translated as tastelessness both in H. Rackham’s translation (for Harvard, 1934) and David Ross’s translation (for Oxford, 1980). Below is a relevant excerpt from Rackham’s translation (see links above):
There are also other dispositions in relation to money, namely, the mode of observing the mean called Magnificence （the magnificent man being different from the liberal, as the former deals with large amounts and the latter with small ones）, the excess called Tastelessness [ἀπειροκαλία] or Vulgarity [βαναυσία], and the defectcalled Paltriness. These are not the same as Liberality and the vices corresponding to it; but the way in which they differ will be discussed later. (Aristotle in 23 Volumes, Vol. 19, translated by H. Rackham. Cambridge, MA, Harvard University Press; London, William Heinemann Ltd. 1934.)