ne sutor ultra crepidam
A phrase I read today and need to apply heartily to my own life and work.
Apparently the phrase means “Cobbler, no further than the sandal!” The story goes that a painter once asked a cobbler for advice on how to correctly paint the sandals of a soldier in a painting he was working on. When the cobbler proceeded to give advice on other aspects of the painting the painter chastised him with the above line. It apparently later became a proverb with a broader meaning of not offering your opinion on matters outside your area of competence.