It's not the gay coat that makes the gentleman.

Understand the thought

Meaning in plain English

An impressive appearance does not establish good character or considerate conduct. The bright coat questions an outward sign of status, without making plain clothing a guarantee of virtue or judging people by a different appearance.

What the words are saying

The gay coat is a showy or fine-looking garment in the image, while gentleman points to a claim about standing and conduct. The proverb separates an impressive outward presentation from the qualities someone actually demonstrates. Figuratively, a polished introduction, expensive setting or attractive design can create an expectation that still needs evidence. The historical class label should not become a modern standard of whose life has worth. Nor does the saying reverse the mistake by treating a modest appearance as proof of good character. Look at actions, consideration and relevant qualities rather than using either display or plainness as a shortcut.

Everyday example

A new committee member gives an elegant introduction, but the group assesses their reliability through how they fulfil agreed tasks and treat fellow volunteers.

When to use it

Use it when impressive presentation is being mistaken for demonstrated character or conduct.

Agent-assisted editorial interpretation. This explains the words; it does not by itself verify their author or earliest origin.