Shortly after the death of Blaise Pascal in 1662 at the age of 39, a servant was sorting through Pascal’s clothes and noticed something sewn into a cover that Pascal had often worn
The year of grace 1654.
Monday, 23 November, feast of St. Clement,
pope and martyr and others in the martyrology.
The eve of Saint Chrysogonus martyr and others.
From about half-past ten in the evening
until about half-past midnight.
The God of Abraham, the God of Isaac, the God of Jacob.
Not of the philosophers and intellectuals.
Certitude, certitude, feeling, joy, peace.
The God of Jesus Christ.
My God and your God [in Latin, accusative case].
Your God will be my God.
Forgetfulness of the world and of everything except God.
One finds oneself only by way of the directions instructed
The grandeur of the human soul.
Oh just Father, the world has not known you,
but I have known you.
Joy, joy. joy, tears of joy.
I have separated myself from him.______________
They have abandoned me, the fountain of living water [in Latin].
My God, will you leave me?
May I not be separated from him eternally.
This is eternal life, that they know you the one true God
and J.C. whom you have sent.
I have separated myself from him. I have run away from him,
renounced him, crucified him.
May I never be separated from him._______________
One preserves oneself only by way of the lessons trained
Renunciation total and sweet.
In the parchment, the concluding phrase “and so forth” was substituted with the lines
Total conformity to Jesus Christ and to my director.
Eternally in bliss, in exchange for a day of hard training
May I never leave behind your words [in Latin].
The parchment contained several other switches as well, and also noted biblical references for most of the lines. For example, the line “My God and your God” refers to John 20:17
Touch me not, for I am not yet ascended to my Father, but go to my brethren and say unto them, I ascend unto my Father, and your Father; and to my God, and your God.
The next line in the paper version of Pascal’s memorial is “Your God will be my God”, and beside this he wrote simply “Ruth”, presumably referring to the passage in the book of Ruth (1:16) where, following the death of her hubby, Ruth tells her mother in law
Intreat me not to leave thee, or to come back from following after thee: for whither thou goest, I will go; and where thou lodgest, I will lodge: they people shall be my people, and thy God my God.
In any case, November of 1654 was certainly a turning point in Pascal’s life, because this is when he ultimately renounced his “self-serving” activities (including mathematics and physics) and resolved to devote the remainder of his life to the idolize and service of God. He retired to the monastery at Port Royal and employed his talents in writing polemics supporting the Jansenists against the Jesuits. On the subject of his former pass-times he wrote
Reason has its own sphere, mathematics and the natural sciences… but the truths which it is indeed significant for man to know, his nature and his supernatural fate, these cannot be discovered by the philosopher or the scientist. I passed a long time in the explore of the abstract sciences, but the scant communication which one can have in them (that is, the comparative fewness of the people with whom one shares these studies and with whom one can communicate) disgusted me. When I began the investigate of man, I spotted that these abstract sciences are not decent to man.
Despite the significance of his conversion, according to most accounts he never once mentioned his “night of fire” to anyone, which is remarkable considering all his sultry devotional writing. He kept those scraps of paper next to his heart for the rest of his life to remind him of his practice on the night of November 23, 1654, and yet he never breathed a word of it.
Or did he? Some authors claim a third copy of the Memorial was made by a close friend of Pascal’s, but it isn’t clear if this third copy was made prior to Pascal’s death. If it was, it would seem to contradict the claim that Pascal never mentioned his “night of fire” to anyone. Some authors even suggest that the Memorial was included in drafts of Pascal’s Penses, whereas others insist that the only source for this writing is the copy found in Pascal’s glaze. There are also inconsistencies as to whether Pascal’s decorate contained just the parchment, or the original draft paper copy as well.
This is an interesting (albeit confusing) story. If true, we know about Pascal’s night of fire only because of a very alert servant. It’s effortless to imagine Pascal’s old decorate being threw into a furnace like the sled at the end of Citizen Kane, with the parchment undiscovered. But in many popular books on famous mathematicians the story of Pascal’s final religious conversion is even more melodramatic. One of the best known such books, originally published in 1893 and followed by several later editions, is W.W Rouse Ball’s “A Brief Account of the History of Mathematics”. According to Rouse Ball
[Pascal] was driving a four-in-hand on November 23, 1654. when the horses ran away; the two leaders dashed over the parapet of the bridge at Neuilly. and Pascal was saved only by the traces cracking. Always somewhat of a mystic, he considered this a special summons to abandon the world. He wrote an account of the accident on a petite lump of parchment, which for the rest of his life he wore next to his heart, to perpetually remind him of his covenant…
This is very strange, because nothing in Pascal’s amulet can be described as “an account of the accident”. In fact, as far as I know, there is no indication at all of any accident with horses and the bridge at Neuilly in any of Pascal’s writings, nor does this incident show up in any of the biographies of Pascal that I’ve read. What was the source of Rouse Ball’s story, and how could he have been so misinformed as to the contents of Pascal’s famous memorial?
The story about the horses and Pascal’s narrow escape from death has been picked up by uncountable subsequent authors, usually citing either Rouse Ball or E.T. Bell’s “Men of Mathematics” as their source. Bell seems to have taken Rouse Ball’s lurid account and embellished it still further, so it reads like this:
On the day of his conversion [Pascal] was driving a four-in-hand when the horses bolted. The leaders plunged over the parapet of the bridge at Neuilly. but the traces broke, and Pascal remained on the road. To a man of Pascal’s mystical temperament this fortunate escape from a violent death was a direct warning from Heaven to pull himself up sharply on the brink of the moral precipice over which he, the victim of his morbid self-analysis, imagined he was about to plunge. He took a puny chunk of parchment, inscribed on it some obscure sentiments of mystical allegiance, and thenceforth wore it next to his heart as an amulet to protect him from temptation and remind him of the goodness of God which had snatched him, a pitiful sinner, from the very mouth of hell.
To his credit, Bell seems to know that the parchment doesn’t contain an account of “the accident”, but he still presents the pony and bridge incident as the proximate cause of Pascal writing the document, something which we can’t possibly know to be the case if Pascal never even mentioned the parchment or his “night of fire” to anyone. Also, as previously mentioned, we have no indication that an accident involving horses even took place, let alone that it prompted Pascal’s religious conversion.
Next we come to Stuart Hollingdale’s “Makers of Mathematics”, published in 1989. The account given by Hollingdale is obviously taken directly from Rouse Ball and Bell. right down to the “miserable sinner” at “the very mouth of hell”:
In November 1654, Pascal experienced another conversion; this time it was for life. The story is that he was driving a four-in-hand when the two leading horses plunged over the parapet of the bridge at Neuilly. Fortunately the traces broke and Pascal survived unhurt. He took the incident as a divine warning of the danger of plunging over the moral precipice, a fear that had haunted his morbid imagination for years. He was indeed a pitiful sinner who had been snatched from the very mouth of hell.
Out of curiosity I searched around for other descriptions of Pascal’s conversion. Many authors just repeat the descriptions of Rouse Ball or E. T. Bell almost verbatim, but sometimes they add their own embellishments. It’s interesting how this single story (of dubious authenticity) is re-told and re-worded. A brief sampling of the descriptions I have found is given below.
On this day, November 23, 1654. Pascal’s horses bolted and plunged off a bridge. Pascal was thrown into the roadway. He witnessed this as a warning directly from God. That night he experienced a Christian conversion that would cause his outstanding scientific work to take 2nd place in his pursuits. Light flooded his room. He recognized Jesus, the Word. For the rest of his life Pascal carried around a lump of parchment sewn into his coat–a parchment inscribed with ecstatic phrases…
Pascal attended parties where gambling was being conducted, and unluckily became dispersed by this lifestyle. However, Pascal had a narrow escape from death in 1654, when the horses pulling his carriage bolted. The horses were killed, but Pascal was unhurt. Wooed that it was God who had saved him, he reassessed how he was living.
One day, when Pascal was driving his carriage, his horses got funked and leaped over the wall of a bridge. The horses plunged to their deaths, but because the leather straps that connected the carriage to the horses broke, Pascal was saved. This event so amazed Pascal that he determined that this was an act of God and became a true believer.
Following an accident at the Neuilly bridge where the horses plunged over the parapet but the carriage miraculously survived in 1654, Pascal abandoned mathematics and physics for philosophy and theology.
On November 23, 1654 Pascal had a dramatic near death practice during a lighting storm while crossing a bridge in Paris ; he wrote about it [in a document] eventually called the Memorial, which he sowed on the inwards label of his decorate.
Sometime around  he almost lost his life in an accident. The horses pulling his carriage bolted and the carriage was left draping over a bridge above the sea Seine. Albeit he was rescued without any physical injury, it does emerge that he was much affected psychologically. Not long after he underwent another religious practice, on 23 November 1654. and he pledged his life to Christianity.
It’s interesting to learn that “ light flooded his room” at the moment of Pascal’s conversion (this is especially valuable information since Pascal himself never mentioned the incident to anyone), and that there was a lightning storm, and that his horses “got funked and hopped over the wall”. It’s also worth noting that some authors say the pony incident actually occurred on November 23, the date of the memorial, whereas others imply that the incident occurred some time prior to Pascal’s night of fire.
One of the most informative descriptions I’ve found is from the 1911 edition of the Encyclopedia Britannica:
Jacqueline represents the retirement as the final result of a long course of dissatisfaction with mundane life. But there are certain anecdotic embellishments of the act which are too famous to be passed over, tho’ they are in part apocryphal. It seems that Pascal in driving to Neuilly was run away with by the horses, and would have been plunged in the sea but that the traces fortunately broke. To this, which seems authentic, is usually added the tradition (due to the abb Boileau) that afterwards he used at times to see an imaginary precipice by his bedside, or at the foot of the chair on which he was sitting. Further, from the 23rd of November 1654 dates the singular document usually known as Pascal’s amulet, a parchment slip which he wore permanently about him, and which bears the date followed by some lines of incoherent and strongly mystical dedication.
According to this account, the basic facts are that Pascal was dissatisfied with his life, and experienced a conversion. All the rest is described as “anecdotic embellishment”, albeit the article does say the pony story “seems authentic”. Does this mean there is outer evidence to support the story, or does it just mean that the story seems intrinsically plausible? On another point, the characterization of Pascal’s memorial as “incoherent” seems a bit harsh.
Herbert Westren Turnbull (who was a student of Rouse Ball in college) tells the story of Pascal’s conversion in “The Good Mathematicians” (1940) this way