On the Tranquillity of the Mind is an ancient “self-help” manual in which Seneca gives his friend Serenus a philosophical advice on how to cope with mental disturbance. For this reason, this writing can also be used to reflect on the current Covid-19 pandemic. Indeed, the disturbance of the mind often arises because we think that we have the events of the external world in our own hands. Seneca, however, disagrees with this view because we have no control over the emergence of some circumstances through the action of “fortune” (lat. fortuna). Through the use of reason and cognitive training of our minds, however, we can overcome this harmful idea. Thus, On the Tranquillity of the Mind can provide us with an ancient guide on how to prepare for unexpected events and thus maintain our tranquility of mind.