The coat makes the man

What others think of us is important. Only the very wealthy and the hermit can afford to ignore public opinion.

In the hurly burly of life it is often not possible to get to know someone in the time available so we make snap judgments. This is often influenced by their way of dressing.

The most obvious case of this is a person in uniform: we regard a man in a sailor's suit to be a sailor; a lady in a police uniform to be an officer of the law, etc.. Business people who wish to convey to others their serious intent usually dress in a sober suited manner whereas a show business host might be more flamboyant.

Not only does the dress convey a message it also helps the wearer to "get into the role" and adopt a mindset appropriate to the occasion.

This saying can be used contemptuous, implying the individual is not worthy of their office and only command respect because of their uniform or position.