What is the source of wearing black veil?

The purpose of dressing the dead in mourning in ancient times is very different from today. The ancients wore mourning clothes to disguise themselves and prevent death from recognizing them.

In many primitive peoples in ancient Europe, relatives of the deceased would dress up in disguise, or put on black mud, hay clothes or black cloth. Its purpose is to scare away death or prevent ghosts and gods from recognizing themselves. Later, the purpose of wearing mourning evolved into expressing condolences to the dead. There was a custom in ancient Europe that when a nobleman died, his servants would wear black mourning clothes for him to show their condolences. On one occasion, some servants in Britain could not afford to buy mourning clothes, and first proposed to wear a black veil on their left arm to show their condolences. This frugal and simple method of mourning for the dead soon spread all over Europe, and then all over the world, and it has been used ever since.