Barefooted men should not tread on thorns.

A person who is especially vulnerable to a particular danger should take care not to encounter it needlessly. The thorns represent a hazard that someone properly equipped might withstand.

The proverb places responsibility on the vulnerable person to recognize their exposure and act cautiously. It favors avoiding a foreseeable injury over testing whether one can endure it.

Use it to advise someone against entering a risky situation without the means to protect themselves, especially when the danger is apparent and can be avoided.