In the Basilica of San Francesco in Siena, 223 consecrated Hosts are kept intact for 276 years. Archbishop Tiberio Borghese closed unconsecrated hosts in a sealed tin box for ten years. The scientific commission put in charge when the box was reopened, found only worms and rotted fragments.
The Siena event is against any physical and biological law, the scientist Enrico Medi stated; "This direct intervention from God is the miracle [...], accomplished and maintained for centuries, to testify to the permanent reality of Christ in the Eucharistic sacrament".
Among the most important documents that describe the miracle, there is a memoir written by a certain Macchi in 1730, in which he written on August 14, 1730 some thieves were able to enter San Francesco's Church in Siena, and stole the chalice containing 351 consecrated Hosts.
After three days, on August 17th, in the alms box of the sanctuary of Santa Maria in Provengano, in the dust, were found the 351 consecrated Hosts intact. The entire population celebrated the finding of the consecrated Hosts which were right away taken back to the church of San Francesco in a solemn procession.
With the passing of time the Hosts were not altered. Many times, distinguished men examined them with every means available and the conclusions were always the same: "The sacred Hosts are still fresh, intact, uncorrupted, chemically pure, and do not present any sign of alteration". In 1914, Pope St.
Pius X authorized a test to which many professors of health, chemistry and pharmaceutics, among whom was also the well-known Professor Siro Grimaldi.
The final conclusion of the edited report stated: "The sacred Hosts of Siena are the classic example of the perfect conservation of particles from unleavened bread consecrated in the year 1730, and constitute a unique phenomenon, full of interest which reverses the natural laws of conservation of organic matter. [...] It is strange, surprising, abnormal; the laws of nature have been reversed, in the glass there was mold, the unleavened bread has been more refractory of the crystal [...] it is a unique fact contained in the annals of science."
Additional tests were done in 1922, in occasion of the Hosts in a cylinder of pure crystal, in 1950 and 1951, Pope John Paul II, during a visit in the city of Siena on September 14, 1980, said regarding the Hosts: "It is the Real Presence!" The permanent miracle of the sacred Hosts is kept in the Chapel Piccolomini in the summer months and in the Chapel Martinozzi in the winter months.
Numerous are the initiatives that induce the citizens of Siena in honor of the sacred Hosts: the tribute of the political districts, the respect of children having recently made their First Holy Communion, the solemn procession in the celebration of Corpus Christi, the Eucharistic ceremony at the end of September, the day of the Eucharistic adoration of the 17th of each month in memory of the finding of August 17, 1730.
Fourteen tests were made to verify the condition of the Hosts. The most scientific one was the one opened by St. Pius X in 1914, in the presence of many scientists
This painting of Master Stefano di Giovanni, known as il Sassetta, is preserved in England in the Bournemouth Museum in Bonehead Castle. The painting depicts a Carmelite nun, tormented by doubts regarding the Real Presence of Jesus in the Blessed Sacrament, is freed from the devil after receiving Communion