1. A partial shadow, as in an eclipse, between regions of complete shadow and complete illumination.
2. The grayish outer part of a sunspot.
3. An area in which something exists to a lesser or uncertain degree:
“The First Amendment has a penumbra where privacy is protected from governmental intrusion” (Joseph A. Califano, Jr.).
4. An outlying surrounding region; a periphery:
“Downtown Chicago and its penumbra also stand rejuvenated” (John McCormick).
pl. pe·num·brae (-bre) or pe·num·bras
--The American Heritage Dictionary of the English Language.
umbra / penumbra
An 'umbra' is a region of shadow caused by the total obscuring of a light source by an opaque body [i.e., one impervious to the rays of visible light]. . . . A 'penumbra' is a partial shadow cast in the same way but obscuring the light source. . . . 'Umbra' is simply Latin for 'shadow'; the 'pen-' of 'penumbra' means 'almost (Latin paene), in the same way as for a 'peninsula', which is 'almost an island.'
--A Dictionary of Contrasting Pairs. Adrian Room. New York: Routledge, 1988 (258).
--Image from (http://www.schorsch.com/kbase/glossary/penumbra.
The word penumbra caught my attention while reading the story of the annihilation of the volcano-island Krakatoa and the huge ensuing tsunami that killed nearly forth thousand people in Krakatoa: The Day the World Exploded, August 27, 1888 by Simon Winchester, a meticulous researcher and superb stylist.
In the chapter titled "Close Encounters on the Wallace Line," Wincester claims (with convincing evidence) that geographer "Alfred Russel Wallace [ pictured at right ], along side Charles Darwin but always as his satellite, is the other true but largely unremembered pioneer of the science of evolution" (56). In this chapter Winchester uses three metaphors to highlight Wallace's significant discoveries and unfortunate rare recognition for them. The most striking of the metaphors makes use of penumbra.
The first metaphor you've already read above, in which Wallace is likened to a satellite within the gravitational pull of Darwin, the planet. The second metaphor is of a higher rank, I'd suggest, because it is attached to a statement of Wallace's independent development of two of the key principles of evolutionary theory. Here we have a penumbral image of diminishing shadow, in which Fame, which is likened to a beacon, casts its bright favor directly upon Darwin, leaving Wallace to stand in the penumbra:
[Wallace's] keen conviction remained, for all of the eight years he spent there [the East Indies], that evidence could be found in this archipelago would substantiate his two growing beliefs: that geography was highly influential in the development of biology, and that species originated by the natural selection of favored types from within the variations of any population. He spent the better part of his life seeking to prove both points--and by and large (and in the penumbra of Charles Darwin) he succeeded magnificently (58).The third metaphor involves Winchester's use of punctuation and has nothing directly to do with penumbra. So skip this paragraph and the next if you like. Or read on: The third metaphor likens life to the syntax of a sentence, with Darwin written into choice places, Wallace into less choice places. Notice how Winchester locates Wallace not only metaphorically within the "penumbra of Charles Darwin" but also, grammatically, within the shadows of reductive punctuation, namely, the enclosures of parentheses, suggesting, thereby, symbolically (so to speak) that history presents Darwin "writ large," but Wallace only parenthetically. (A few pages later, Winchester repeats the trope of parentheses, this time drawing the reader's attention to it: "Darwin's discoveries (along with those of Wallace, naturally--these very parentheses serving to remind us how simple it is still to overlook the dyer's son from Usk) had overturned so much of man's own certainty about his own beginnings." (68)
(A quirky thought in passing: What if Wallace had somehow landed within Darwin's umbra? As I investigate the metaphor more closely in terms of its etiology (the study of causation), I . . . well . . . I suppose there would be no Alfred Russel Wallace to write or read about. Nevermind.)
The final metaphor involves Winchester speaking directly to the reader, speaking openly about a second deliberate use of parenthesis as a metaphor for Wallace's secondary status: whereas history presents Darwin writ large, Wallace has to settle with parenthetical status.
--Simon Winchester. Krakatoa: The Day the World Exploded August 27, 1883. New York: HarperCollins. 2003.
If you skipped the last two paragraph, welcome back.
The penumbra as metaphor has been put to use not only in literature, as we've seen, but also in other realms of human experience. Following are two of them.
THE PENUMBRA FONT
The designer of Penumbra (1994)--Lance Hidy--describes it as "an ‘androgynous’ letterform which morphs between the worlds of sans serif and serif" and between the extremes "of contemporary and traditional qualities." Both the concept of morphing between extremes and the state of androgyny work on the analogy of the "unbra to penumbra to light" continuum.
Penumbra was chosen as the signature font for the film "The Da Vinci Code," a world of characters struggling, each in his or her own way, within the penumbric world between the darkness of deception and the light of truth.
Primula polyanthus 'Penumbra'
SILVER LACED PRIMROSE
Lest you think that everything touched by the word penumbra finds itself cast in shadow, consider the bright image of the Penumbra (Primula polyanthus).
Penumbra as the name of a flower springs from one of the definitions of the word we have not been considering--
" . . . the curious slim edge of cool light that shows around the moon during an eclipse.
"Named for the curious slim edge of cool light that shows around the moon during an eclipse, ‘Penumbra’ grows to 10" and is heavenly in woodland gardens. Fragrant ‘Penumbra’ flowers from February to June and is hardy to zone 4."