(NEXSTAR) – At the final Mass at the Vatican Wednesday before the secretive conclave process officially kicked off, a sea of red and purple robes were visible in St. Peter's Basilica.

The wardrobe choices weren't a matter of taste – each robe symbolizes something different.

The red robes are worn by all 133 cardinals deliberating who will replace Pope Francis. The original reason cardinals started wearing red is disputed, but the hue is often said to represent the blood of martyrs or to show cardinals' willingness to die for their religion.

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