On Duties (De Officiis) was written by Cicero in 44 BC. Over the centuries, Church Fathers, emperors, Renaissance humanists and countless others have valued On Duties as an excellent treatise for moral living. In this informal and highly anecdotal letter to his son, Cicero insists that he use only one question to evaluate his conduct: Is it right? Forget pleasure. Forget utility. In fact, Cicero says it is a wicked and fatal deception to place what is morally good against what is truly advantageous. What is right must be advantageous to the soul and vice versa. But how are “right” and “advantageous” to be determined? Look not to pleasure, popularity or profit, but to nature.

For nature demands that all things should be right and harmonious and consistent with itself and therefore with each other. But nothing is less harmonious with nature than wrong-doing: and equally, nothing is more in harmony with nature than what is truly advantageous. So advantage cannot possibly coexist with wrong.

Using nature as a guide to conduct is perhaps more timely now than ever before, as material benefits and gains are usually the only reference points today in the fields of ethics, medical research and technology. We allow research on human embryos with the assurance that it will provide cures for diseases. The ends (possible breakthroughs) justify the means (destruction of human life). Social media makes communication easier, but is it better?

In On Duties, Cicero refers to nature’s “rational principal, the law that governs gods and men alike” as a guide to conduct. It’s fascinating that he places the gods themselves under the governing principle of reason. They may be powerful, but they aren’t higher than nature’s law. In this, it is hard not to hear Benedict XVI’s frequent reference to the “creative Reason/Logos” that is God Himself. God is Reason, and so rational creatures are required to align their will and actions to that which is rational, that is to say, with nature.