On the Feast of the Exaltation of the Cross, I promised a thread summarizing a scientific refutation of John Calvin's haughty and presumptuous claims against the authenticity of relics of the True Cross. A little late, but here it is.

First, you've probably heard Calvin's argument, even if you didn't know the source. In Calvin's 1543 "Traité des Reliques" ('Treatise on Relics') he writes the following, which has achieved a tired and unexamined memetic repetition, like so many arguments of the Reformation:

"There is no abbey so poor as not to have a specimen [of the Cross]. In some places there are large fragments, as at the Holy Chapel in Paris, at Poitiers, and at Rome, where a good-sized crucifix is said to have been made of it...

"In brief, if all the pieces that could be found were collected together, they would make a big ship-load. Yet the Gospel testifies that a single man was able to carry it."

Modern research and the application of scientific reason proves this assertion laughably wrong.

Charles Rohault de Fleury (1801–1875), a French architect and engineer who dabbled in Christian archaeology in his later years, put the claim to the test.

You can find the results of his research in his 1870 book, "Memoire sur les instruments de la passion de N.-S. J.-C." ('Memorial of the Instruments of the Passion of Our Lord Jesus Christ'): https://archive.org/details/InstrumentsPassion

The work contains an erudite summary of all we know, from ancient and medieval sources, of the discovery of the Cross and the diffusion of its relics around the world.

You'll also find some very interesting diagrams summarizing the relative size and format of these relics.

De Fleury's first task was to estimate the volume of the original Cross. He supposed that it would have been perhaps 10 to 13 feet in height, with a cross branch of 6 ½ feet wide, proportions reasonable for the gruesome task of crucifying an adult man.

This also happens to be the size of the cross at the Basilica of Santa Croce in Rome, identified as the Cross of the Good Thief.

Figuring the weight of the Cross would be a little more difficult, as it depends on the type of wood. De Fleury figured that it was pine wood (based on his examination of some of the relics), but also made a guess based on factors recorded in the Gospels.

He reasoned that Jesus, as a fit carpenter, could carry 220 pounds of lumber on his shoulder 150 feet before stopping to rest.

Thus he concluded that the Cross may have weighed about 220 pounds, but since it was probably dragged, it would have *felt* like 55 or 60 pounds.

Nonetheless, in his weakened condition after the scourging, even this modest weight would have been too much for Jesus, and so the Roman guards compelled Simon of Cyrene to help carry the Cross.

Once he had estimated the weight of the Cross, Fleury calculated its size, or more accurately, its volume, which came to 178 million cubic millimeters, or 10,862 cubic inches.

But the total volume of known relics of the True Cross, according to his thorough catalogue (which I encourage you to examine in the scanned book, linked above), amounted to a mere 3,941,975 cubic millimeters, or 240.5 cubic inches.

This number surprised him, so he made a generous allowance for fragments that were in private hands or otherwise had not come to his attention, as well as fragments that had been lost over the centuries or destroyed in war or during the vandalism of the Reformation.

Thus he multiplied his original number by *ten* and arrived at a new figure: perhaps 2,400 cubic inches — still not even a fifth of the estimated size of the Cross upon which Christ was crucified.

And hardly a ship-load.