The acts of the good, as you have said, form virtue. The good, however, are to be known by their acts. The definition, therefore, has at the bottom a begging of the question, and the result is that what is meant by conduct of the good remains unsettled.
सदाचारो मतो धर्मः सन्तस्त्वाचारलक्षणाः। साध्यासाध्यं कथं शक्यं सदाचारो ह्यलक्षणः॥