Giordano Bruno was a brilliant, if eccentric, philosopher, but the life of a Dominican priest in the Catholic Church apparently didn't suit him. He left the order in 1576 and started wandering Europe as a traveling philosopher, lecturing in various universities. His chief claim to fame was the Dominican memory techniques he taught, bringing him to the attention of royalty, including King Henry III of France and Elizabeth I of England. His memory enhancement techniques, described in his book "The Art of Memory" are still used today.
Though outspoken, and perhaps, not truly appreciated while in the Dominican Order, his troubles truly began around 1584 with the publication of his book "Dell Infinito, universo e mondi" ("Of Infinity, the Universe, and the World"). Being a philosopher and not an astronomer, Giordano Bruno would not have even warranted our attention if not for this book and the consequences of it.
Hearing the ideas of Copernicus about the nature of the universe sent Giordano Bruno into a veritable frenzy of philosophical thought. If the Earth was not the center of the universe, and all those stars clearly seen in the night sky were also suns, then there must exist an infinite number of earths in the universe, inhabited with other beings like ourselves.
This idea about the universe did not sit well with the Catholic Church. They lured Giordano Bruno to Rome with the promise of a job, where he was immediately turned over to the Inquisition and charged with heresy.
Giordano Bruno spent the next eight years in chains in the Castel Sant’Angelo, where he was routinely tortured and interrogated until his trial. Despite this, he remained unrepentant, stating to his Catholic Church judge, Jesuit Cardinal Robert Bellarmine, "I neither ought to recant, nor will I." Even a death sentence handed down by the Catholic Church did not change his attitude as he defiantly told his accusers, "In pronouncing my sentence, your fear is greater than mine in hearing it."
Immediately after the death sentence was handed down, Giordano Bruno’s jaw was clamped shut with an iron gag, his tongue was pierced with an iron spike and another iron spike was driven into his palate. On February 19, 1600, he was driven through the streets of Rome, stripped of his clothes and burned at the stake.