Here is Father’s Commentary:
Pope Pius V is one of only three (soon to be four) popes to have been canonized in recent years. He is very significant when we look at the popes today, when we see pictures of Pope Benedict, Pope John Paul, or any popes that we see photographic images of. They’re wearing a cassock made of white. But it hasn’t always been that way.
The first Dominican pope who was elected was Pius V, and he wanted to stay with his humble origins, which were the habits of the Dominican order. And in some cases Dominicans wore all white. Some do wear black, but it was his tradition to wear all white, and so when he was elected he wanted to continue to wear white.
So this artifact is a reliquary that has a portion of his original white cassock.
So after he wore white, every Pope did it in honor of him. So when we see the current popes wearing the white attire, they’re doing it in honor of Pius V, because he was such a great pope and they wanted to keep the tradition of the all white cassock.
Prior to Pius V, their cassocks were red, like cardinals. I’m not sure how popes differentiated themselves from cardinals, because even then cardinals wore red, like the galerro we have in the Collection belonging to Pius XII. The significance of the red was the blood they were willing to spill in protection of the Church.
So it wasn’t until Pius V that the tradition of white was actually started. And of course this is significant, because from that time until the present time they have worn white.
And what we have here is this relic, this piece of cloth that was really part of a trend that was set that is still in place.
Papal Artifacts celebrates the feast of Saint Dominic today and honors the gift to our Church of Saint Pius V.