The International Prime Meridian was not established until 1884. In 1639, Poussin may have used the Paris Meridian to point to Rennes-le-Chateau, so the angles should be 42.9 degrees N and 0 degrees E/W .
King Louis XIII and Cardinal Richelieu re-established, by Royal Decree, the French Prime Meridian in 1634. Richelieu commissioned Poussin in 1635 to paint “The Triumph of Pan” (they knew each other five years before Shepherdess painting) If you are familiar with Poussin's painting; have you looked at the Triumph of Pan? The background looks familiar!!!
What if the Paris Meridian was known to Poussin? That would certainly change things. When I rearranged the angles (using the sides of the fingers instead of their centres, the pointing becomes clearer.
Perhaps they are pointing at 42.9N and 0E (O degrees, relative to the Paris Meridian). Here is what it looks like!
Poussin Pointing the Way to Rennes le Chateau
I may not be "right" about the pointing Shepherds, but at least it points to a simple solution of the Poussin painting.
QUOTE
To paraphrase Occam's Razor: All things being equal, the simplest solution tends to be the best one.
Any comments? I would like to hear what others think of my "discovery". Does it seem valid. Please measure the angles yourself rather than accept mine. I used Visio 2003 and the footer image from Andy Gough's Arcadia website. It would be nice to see it done with another software (Autocad) and another version of the painting.