Looking diagonally across the Carnac alignments. The lines form complex patterns within the line of sight of people who are walking among them.

It is difficult to give meaning to a single standing stone. Many interpretations have been advanced, but there is still not much solid ground to go on.
 
There are four possible explanations for isolated stones (or stones thought to be isolated). They can be:
  • boundary stones marking (and sacralising) either a territorial boundary or the area visually controlled by the stone,
  • memorial steles commemorating a past event or someone important, and often endowed with a more or less mythological significance;
  • baetyls sacralising a particular site. e.g. a high point or, more frequently, a spring or a waterway,
  • axis mundi linking the chtonian and heavenly powers, via the tangible world represented by the earth's surface.
Systems combining several menhirs in more or less complex patterns can give rise to several interpretations.
 
Lines can be viewed from several directions. When seen lengthwise, they can point the way along an initiatory path. When seen diagonally, they can form a (visual) boundary to the "background".
 
Stone enclosures can be interpreted as marking a boundary between a "sacred area" and the surrounding secular areas. This is common in archaic forms of religion. Breton stone enclosures almost always include a wide opening which could have been designed to allow outsiders to "enter the circle". 
Carnac's large groups of standing stones thus combined lines and stone enclosures, seeming to mark out the "sacred area", the "sacred path" leading to the area and a "background" which could change according to the movements of the faithful or of the initiated
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Pedernec Menhir (Côtes-d'Armor department). This is an example of isolated large monoliths located in clearly visible places.

"Ideal" reconstitution of the Carnac alignments. First half of the 19th century

Choices and limits

Should the stones be considered as entire groups or as significant separate entities? People in the Neolithic age must have had an answer to this question. Seen in this light, the traditional depiction of the Carnac alignments as a petrified army of individual soldiers takes on a new meaning .

Were the patterns inspired by geometry or by aesthetics? Astronomy or megalithic metrology have produced somewhat ambiguous results (however convincing they may seem to some). This does not mean, however, that these sciences have nothing to contribute. But research along these lines should also consider the influences of astrology on people attempting to control evil influences, as was the case among many of the peoples of Europe in early Antiquity. 

The visible part of the iceberg? When we look at a menhir today, we have to take into account what we can no longer see (long vanished ancillary structures, such as adjoining menhirs) and what we cannot yet see (invisible structures buried in the vicinity). Only studying the "large stones" visible today, amounts to ignoring an "archaeological iceberg", as was illustrated by the recent excavation carried out at Locmariaquer