The Dan Brown Rosary Collection is the largest collection of rosaries in the world. It is housed in the Columbia Gorge Interpretive Center
in Stevenson, Washington, a very nice little museum on the northern side of the Columbia River Gorge. The museum's focus is on human history of the Gorge, from ancient times until now.
Rosaries are typically constructed with five or fifteen sets of ten beads each. Each of the sets of ten beads is called a "decade", representing a particular series of prayer and meditation. Hence the link to this quarter's theme, although with a non-obvious meaning.
Also not obvious is why a collection of rosaries would be housed in a museum dedicated to the culture and history of the Columbia River Gorge. It turns out that the Gorge has been a place of spiritual questing for many years, and the center's "Spiritual Quest" gallery is devoted to this part of its history. The rosary collection exemplifies this, and although rosaries themselves are not associated with the Gorge, the founder of this collection spent his whole life there.
Rosaries are an example of prayer beads from the Catholic faith, but other forms of prayer beads are used in similar ways by other faiths around the world. According to documentation available at the museum, as much as three-quarters of people worldwide make use of similar items in some way. So as the rosary's decade represents one particular sequence of prayer and meditation out of a series of such sequences, one might say it also represents a step in spiritual journeys, and perhaps stages in life in general.
So this use of decade reflects a step along a journey, just as the first ten years of the WWP are but a step along its own journey, the journey of all those involved, and of VR photography in general.