上以风化下，下以风刺上，主文而谲谏，言之者无罪，闻之者足以戒，故曰风，至于王道衰，礼义废，政教失，国异政，家殊俗，而变风变雅作矣。
Superiors use the Airs to transform those below. Those below use the Airs to criticize their superiors. They stress elegance of expression and remonstrate obliquely: the speaker does not offend, and it allows the hearer to take warning. Thus they are called “Airs.” When the kingly way declined and rites and right action were discarded, when the teaching of governance was lost, so that states had different governance and clans different customs, then the Changed Airs and Changed Ya were made.

国史明乎得失之迹，伤人伦之废，哀刑政之苛，吟咏情性，以风其上，达于事变而怀其旧俗者也，故变风发乎情，止乎礼义。
The state historians clearly knew the traces of success and failure.  They grieved at the discarding of correct human relations and lamented the cruelty of governance using punishment. They sang of their nature and feelings in order to influence their superiors. They penetrated the changes in affairs and cherished the old customs. Thus the Changed Airs come from feelings and yet stop with the bounds of ritual and duty.

发乎情，民之性也；止乎礼义，先王之泽也。
Their coming from feelings reflects the nature of the populace. Their stopping within rites and duty reflects the beneficent legacy of the early kings.

是以一国之事，系一人之本，谓之风；言天下之事，形四方之风，谓之雅。
Thus when the affairs of an entire state are tied to the person of a single individual, we deem this an “Air.” When a poem speaks of the affairs of the realm, giving form to the manners of the four directions, we deem it Ya.

雅者，正也，言王政之所由废兴也。
“Ya” is “correctness”: it speaks of the process by which kingly governance rises and falls. 

政有大小，故有小雅焉，有大雅焉。
In governance there are lesser and greater matters; thus there are the Lesser Ya and the Greater Ya.

颂者，美盛德之形容，以其成功告于神明者也。
The hymns praise the form and appearance of flourishing virtue in order to tell the ancestral spirits of their successes.

是谓四始，诗之至也。
These are called the four beginnings:  they are the perfection of poetry.