Some go to the light of nature and the use of "right reason" (that is, their own) as their guides; and some add the additional documents of the philosophers. They think a saying of Epictetus, or Seneca, or Arrianus, being wittily suited to their fancies and affections, to have more life and power in it than any precept of the Gospel. The reason why these things are more pleasing unto them than the commands and instructions of Christ is because, proceeding from the spring of natural light, they are suited to the workings of natural fancy and understanding; but those of Christ, proceeding from the fountain of eternal spiritual light, are not comprehended in their beauty and excellency without a principle of the same light in us, guiding our understanding and influencing our affections. Hence, take any precept, general or particular, about moral duties, that is materially the same in the writings of philosophers and in the doctrine of the Gospel; not a few prefer it as delivered in the first way before the latter.
Quotes, by John Owen