I read an interesting magazine article written back in February by a couple who took a tour through the Paleolithic Niaux Caves in France. The cave contains 13,000-year-old drawings which the authors called “masterpieces.” In fact, the title is:
The idea that perspective was invented in Florence in 1414 collapsed in an instant. Here, larger mammals are in front of smaller ones who trail behind; animals at the back of packs are smaller than those in front. . . Elsewhere, an Ibex is depicted from behind and over the shoulder—an in incredibly sophisticated perspective. One horse is seen from highly accomplished three-quarters view. Imagery seemed adjusted for curvature and protrusions of the walls in the same ways that Renaissance frescoes adjust for distortions, distance, and odd viewing angles. . . The shading I saw on the rear hoof and fetlock of a bison, the first thing that I set eyes on when our guide shined her light in the gallery, never leaves me. It is the punctum—the flash point—of the caves for me.
I venture that when it comes to the best of these paintings, mammals have never been rendered better in the history or our species. [[I’m sure the authors are thrilled I think that here they’re a bit over the top.]]
The shading I saw on the rear hoof and fetlock of a bison, the first thing I set eyes on when our guide shined her light in the gallery, never leaves me. It is the punctum—the flash point—of the caves for me.
I venture to say that when it comes to the best of these paintings, mammals have never been rendered better in the history of our species. [[Oy vey!]]
So what’s a punctum – never heard of it! But, if we are to believe the author wants it to mean ‘flash point' then I don't know if he thinks it is known with his meaning to a select few 'erudites' as him or he's trying to coin a new meaning.
AMERICAN HERITAGE DICTIONARY
FLASH POINT or FLASHPOINT noun: The point at which eruption into significant action, creation, or violence occurs: <The shootdown did not increase international tensions to the flash point.> [[And this is the only meaning of ‘flashpoint’ that I’m aware of.]
MERRIAM-WEBSTERS UNABRIDGED DICTIONARY
1) obsolete : POINT [[see OED (1), below]]
2) A small area marked off in any way from a surrounding surface : dot, puncture <A punctum in a fossil shell> <Insect bites that may show the central tiny hemorrhagic punctum>— Journal American Medical Association
Note: American Heritage Dictionary and Random House Webster’s Unabridged Dictionary do not even list punctum, so we probably don’t have a real barnburner here, but Google does claim 617,000 hits (at my space-time coordinates). But take a look at the pathetic three pages of, as they say, “the most relevant results” they have found – again, makes one wonder about the false impression Google often tends to give. And even though their number may be technically accurate, the number of repeats is often enormous.
Here is a sampling of what the OXFORD ENGLISH DICTIONARY had to say (updated September 2007):
Etymology: <classical Latin punctum>
1a) [before 1592] obsolete: A geometrical point in space; a mathematical point.
2b)  obsolete: A very small division of time, an instant.
2c) [before 1680]: The essence of a matter or thing, the most important focus of attention or consideration; (also) a point for discussion, a proposition.
3) : Originally point used as a punctuation mark (now obsolete), a full stop.
4) : Chiefly Zoological, Botanical, and Medical. A minute rounded mark or object; a speck, a dot; a small rounded spot of colour; a small elevation or depression on a surface.
5) : Anatomy. More fully lacrimal punctum. The tiny circular orifice of each of the lacrimal ducts, situated on the margin of each eyelid near the medial commissure.
6)  In Western plainsong notation: a neume or part of a neume signifying a single note, usually written as a dot. [[‘neumen’: A sign used in the notation of plainsong during the Middle Ages, surviving today in transcriptions of Gregorian chants.]]
7) a) Early Music : A closing inflection used in the chanting of lessons or prayers in Christian liturgy, often entailing a descent from the monotone reciting note. Now rare. b) 1879]: In Western plainsong notation: a neume or part of a neume signifying a single note, usually written as a dot.
So much for the OED, which is good stuff. But to see how people more ‘commonly’ use the word today, I tried taking a look at some more ‘with-it’ dictionaries which inched a little closer – but no cigar – to the author’s usage (coinage?). The definition is no help, although the sample sentences inch a little closer to his drift.
Technical: A small distinct point.
“Barthes writes, ‘However lightning-like it may be, the punctum has, more or less potentially, a power of expansion.’”
“In view of the history of recurring meningitis, search of the child's skin then showed a small punctum in the back of the neck.”
“For Barthes, the catastrophe is unavoidable because time obliterates the punctum, or small space, registered in the photograph.”
Anatomy: The opening of a tear duct.
Punctum, functum, plunctum, . . . flashpoint? – seems like an effort by the author to introduce a word he heard somewhere, possibly from some literati folks. Maybe he couldn’t quite think of one that expressed what he really wanted to say. And perhaps he was thinking that he would attain acclaim with his coinage or whatever. The dashes around flash point would point out to those select few who already knew the meaning of punctum that he was defining it for the masses who didn’t know, or if he lucked out he could claim the dashes as a sign of his coinage if no one else stepped up and claimed ownership, But, nonetheless, it can’t be denied that it was a great and thrilling discovery that the author writes about and which obviously got him ‘all shook up’ (did I just coin that or did I hear it someplace?) (<:)
Ken G – July 15, 2015