Do not bite off more than you can chew...

Donald's Commentary on The Handbook of Epictetus #37

If you undertake a role which is beyond your powers, you both disgrace yourself in that one, and at the same time neglect the role which you might have filled with success.

Commentary

We all adopt different roles in life, which depend on our ability to influence external events, in various ways. Epictetus seems to mean that if we’re going to undertake roles where we’re expected to manage people or events appropriately then we should first be certain that this is within our power. Otherwise, it’s as though we’re making a promise that we don’t know if we can keep.

I don’t think he’s talking about external success so much as fulfilling a role in accord with wisdom and virtue. He presumably means that we disgrace ourselves when we undertake tasks beyond our power because fear or temptation lead us astray. For example, some people would have the wisdom and temperance to endure political office without being corrupted, whereas others would find it stressful and would be tempted to abandon their principles. How do we know that it is within our power to fulfil a role without being corrupted? We can only learn this through self-observation and experience.