When Celsus here or elsewhere finds himself unable to dispute the truth of what we say, but avers that the same things were said by the Greeks, our answer is, that if the doctrine be sound, and the effect of it good, whether it was made known to the Greeks by Plato or any of the wise men of Greece, or whether it was delivered to the Jews by Moses or any of the prophets, or whether it was given to the Christians in the recorded teaching of Jesus Christ, or in the instructions of His apostles, that does not affect the value of the truth communicated.
It is no objection to the principles of Jews or Christians, that the same things were also said by the Greeks, especially if it be proved that the writings of the Jews are older than those of the Greeks. And further, we are not to imagine that a truth adorned with the graces of Grecian speech is necessarily better than the same when expressed in the more humble and unpretending language used by Jews and Christians, although indeed the language of the Jews, in which the prophets wrote the books which have come down to us, has a grace of expression peculiar to the genius of the Hebrew tongue.
And even if we were required to show that the same doctrines have been better expressed among the Jewish prophets or in Christian writings, however paradoxical it may seem, we are prepared to prove this by an illustration taken from different kinds of food, and from the different modes of preparing them. Suppose that a kind of food which is wholesome and nutritious has been prepared and seasoned in such a way as to be fit, not for the simple tastes of peasants and poor labourers, but for those only who are rich and dainty in their tastes.
Suppose, again, that that same food is prepared not to suit the tastes of the more delicate, but for the peasants, the poor labourers, and the common people generally, in short, so that myriads of persons might eat of it. Now if, according to the supposition, the food prepared in the one way promotes the health of those only who are styled the better classes, while none of the others could taste it, whereas when prepared in the other way it promoted the health of great multitudes of men, which shall we esteem as most contributing to the public welfare—those who prepare food for persons of mark, or those who prepare it for the multitudes?— taking for granted that in both cases the food is equally wholesome and nourishing; while it is evident that the welfare of mankind and the common good are promoted better by that physician who attends to the health of the many, than by one who confines his attention to a few.
Source: Against Celsus (New Advent)