The best way to discover our duty is to study the divinely inspired Scriptures, for in them we find both instructions about conduct and the lives of blessed men, delivered in writing. They are laid before us like having images of the godly life for the imitation of their good works. When we devote ourselves to the imitation of what is offered there, we find the appropriate medicine for whatever deficiency or illness we feel we have, as from a pharmacy.
Basil was Bishop of Caesarea in Cappadocia from 370-379. This quote is from Everett Ferguson, Inheriting Wisdom, Readings for Today from Ancient Christian Writers. Peabody: Hendrickson, 2004, pages 228-229.