He who cannot be known from himself, may be known from his associate.

Explanation

(English-origin maxim.) When a party cannot be identified on his own, his identity may be established through his known associates — cite this in tracing the identity of an unknown principal through his agent or confederate.

Where this applies

• Police cannot identify an anonymous caller who made a bomb threat, but they trace his identity through the known associates he called immediately before and after the threat.
• A mystery investor behind a shell company is identified by investigators through his longtime business partner who is already known to them.
• An unregistered foreign agent is unmasked by his connection to a known diplomat, because a man who cannot be identified on his own may be identified through his associates.